BGD Tutorial - Applied Embryology and Teratology

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Introduction

Chris.jpg
This Medicine Phase 2 tutorial introduces the topics of Applied Embryology and Teratology. This one and a half hour presentation uses your existing knowledge of normal human development in an applied clinical manner in relation to our existing knowledge of teratogens. In addition, you should begin considering the variables that will not change and those that will in future medical practice. Due to time limitations, only a brief coverage can be given of any one topic.


Self-Directed Learning boxes on this page will not be discussed within the tutorial. You should also return here and later work through the linked online resources for more detailed descriptions and an understanding of these issues. This current page appears in the lefthand menu under Medicine as BGD 2 Tutorial.


2018 Tutorial PDF       Tinycc page - http://tiny.cc/BGD2_Tutorial


Similar content was covered in the previous online tutorials in 2017 | 2016 | 2015 | 2014 | 2012 | 2015 PDF | 2014 PDF | 2012 PDF | 2011 PDF and 2010.

Whats in the News?  
Pregnancy Care Guidelines 2018

This edition brings together the two previous modules and contains updates of a number of topics from them, including weight and body mass index (weight monitoring reviewed), fetal growth and wellbeing, risk of preterm birth, risk of pre-eclampsia (risk factors and prediction reviewed), family violence, hyperglycaemia (early testing reviewed), hepatitis C, thyroid dysfunction, vitamin D status and chromosomal anomalies (cell- free DNA testing reviewed). The new topic substance use has also been incorporated.

See also The Australian Immunisation Handbook 10th edition (2015) Canberra: Australian Government Department of Health. ISBN: 978-1-74241-861-2 Online ISBN: 978-1-74241-862-9..
Aus-Imm-Handbook-2015.jpg

  • drugs - Maternal antibiotic exposure during pregnancy and hospitalization with infection in offspring: a population-based cohort study[2] "The early life microbiome contributes to immune development. Antibiotics during pregnancy alter the microbiome and may influence disease risks in the offspring. We investigated the relationship between maternal antibiotic exposure before and during pregnancy, and risk of childhood hospitalization with infection. METHODS: We used population-based Danish national databases for pregnancies between 1995 and 2009. ...Antibiotic exposure before or during pregnancy was associated with increased risk of childhood hospitalized infections. Alteration of the maternally derived microbiome and shared heritable and environmental determinants are possible contributory mechanisms."
  • Assisted Reproductive Technology - New research shows that women who start the IVF process while aged between 30 to 34 have a 43.4 per cent chance of a live birth. Med J Aust 2017; 207 (3): 1. doi: 10.5694/mja16.01435 MJA - ABC - SMH
Australia - insulin-treated diabetes by type 2015
Australia - insulin-treated diabetes by type 2015

Incidence of insulin-treated diabetes in Australia 2015 [3] provides the latest available national data on new cases of insulin-treated diabetes in Australia.

It shows that in 2015 there were 28,775 people who began using insulin to treat their diabetes in Australia:

  • 63% had type 2 diabetes
  • 26% (18,142) had gestational diabetes
  • 9% had type 1 diabetes
  • 2% had other forms of diabetes or their diabetes status was unknown.

In 2015, 7,405 women began using insulin to manage gestational diabetes—130 cases per 100,000 women of reproductive age (15–49 years), or around 1 in every 800 women aged 15–49. This represents almost 1 in 4 (24%) women diagnosed with gestational diabetes aged 15–49 in 2015.

Gestational diabetes occurs when higher than normal blood glucose is diagnosed for the first time during pregnancy. It generally occurs in the second or third trimester, among women who have not previously been diagnosed with other forms of diabetes.


Community immunity cartoon.jpg
Postnatal - Vaccination - 2011 ABC - Autism vaccine study 'an elaborate fraud'
  • Australian Health - Vaccination Data Hub "The disease which requires the highest level of vaccine coverage to achieve herd immunity is measles as it is highly infectious. It is estimated that coverage of 92-94% is required for herd immunity from this virus"
  • Measles (rubeola) is a paramyxovirus appearing mainly as a respiratory viral infection, clinically different from Rubella. A single-stranded RNA virus which is highly contagious. Before measles vaccination (USA 1963) more than 90% of children had an infection before puberty and in developing countries it is still a common and often fatal childhood disease. Childhood immunisation and immunity persists in only about 80% of adults.
  • Pregnancy effects of measles results in a higher risk of premature labor, spontaneous abortion, low-birth-weight, and possibly rare cases of birth defects with no definable pattern of malformation.[4]
News - Australian Screening for Spinal Muscular Atrophy
NSW Newborn Screening Programme
SMA added to newborn heel prick (Guthrie test) "In an Australian first, newborn babies are now being routinely screened for the genetic condition SMA, or spinal muscular atrophy". SMA leads to a loss of motor neurons and progressive muscle wasting and has several different forms: Type 1, Type 2, and Type 3a SMA. ABC News



Neonatal Diagnosis Links: neonatal diagnosis | Apgar test | Guthrie test | hearing test | Electrocardiogram (ECG/EKG) | X-ray | Tandem mass spectrometry | Classification of Diseases



Older News Articles - Australian 2018 Pregnancy Care Guidelines | CRISPR | Gestational Diabetes | Kyoto eBook | Dolly's sisters live on! | Thalidomide in Zebrafish | Human pancreas stem cells | Oral contraceptive no risk of major birth defects | Maternal Malaria Neurovascular Development Effects | Oocyte/Spermatozoa fate decision Rubella eliminated in the Americas | Three-person embryos
AIHW Report - Folic acid and iodine fortification (2016)
Folic acid and iodine fortification (2016)[5]


  • Mandatory fortification of bread with folic acid (in Australia) and iodine (in Australia and New Zealand) was introduced in 2009
  • Overall decrease in the rate of neural tube defects (NTDs) by 14.4%
  • Teenagers the rate of NTDs decreased by almost 55%
  • Aboriginal and Torres Strait Islander women the rate of NTDs decreased by 74%
Links: Folic Acid and Neural Tube Defects | Iodine Deficiency | Australian Statistics | AIHW - folic acid and iodine
ZIKA Virus
Zika virus world map (CDC 2016)Mosquito lifecycle
Zika virus (ZIKV) is a mosquito-borne flavivirus related to dengue virus first isolated from a rhesus monkey in Zika forest, Uganda (1947). Transmitted by mosquitoes (Aedes aegypti) it was then identified in humans in Nigeria in 1954 and subsequently in South America, Asia and Pacific regions. More recently in Australia from returning travellers.[6] Mosquito bites lead to an initial infection of skin cells.[7] The virus may also be transmitted transplacentally or during delivery.[8] Some limited evidence, from Brazil, for association with microcephaly. (More? Abnormal Development - Zika Virus | Abnormal Development - Viral Infection)
Pertussis (whooping cough) Increase
NSW-pertussis-notification-graph 2012-16.jpg
There has been a recent significant increase in the total number of pertussis (whooping cough) notifications in NSW, Australia.


Pertussis (whooping cough, 100-day cough) is a highly contagious bacterial (Bordetella pertussis) infection prevented by vaccination with the pertussis vaccine. Symptoms are initially similar to the common cold. Neonatal infection can be fatal, with 1% of infected infants under one year of age dying, other complications include: pneumonia (lung infection), convulsions (violent, uncontrolled shaking), apnea (slowed or stopped breathing) and encephalopathy (disease of the brain). (More? Postnatal - Infectious Diseases School Exclusion | Neonatal Development | Abnormal Development - Bacterial Infection)


Objectives

Human Embryonic Development (week 1 to 8)

Applied Embryology: birth statistics, unintended pregnancies, ART, abnormalities statistics, timeline of development, trophoblastic disease, embryonic development, placenta, fetal development, maternal diet, multiple pregnancies.

Teratology: definitions, critical periods, medications, chromosomal abnormalities, environmental factors and infections.

Textbooks

Logo.png Hill, M.A. (2018). UNSW Embryology (18th ed.) Retrieved October 19, 2018, from https://embryology.med.unsw.edu.au
Diagnosis Links: Prenatal Diagnosis | Pregnancy Test | Amniocentesis | Chorionic villus sampling | Ultrasound | Alpha-Fetoprotein | Pregnancy-associated plasma protein-A | Fetal Blood Sampling | Magnetic Resonance Imaging | Computed Tomography | Non-Invasive Prenatal Testing | Fetal Cells in Maternal Blood | Preimplantation Genetic Screening | Comparative Genomic Hybridization | Genome Sequencing | Neonatal Diagnosis | Category:Prenatal Diagnosis | Fetal Surgery | Classification of Diseases | Category:Neonatal Diagnosis
neonatal diagnosis
Abnormality Links: abnormal development | abnormal genetic | abnormal environmental | Unknown | teratogens | ectopic pregnancy | cardiovascular abnormalities | Coelomic Cavity | endocrine abnormalities | gastrointestinal abnormalities | genital abnormalities | head abnormalities | integumentary abnormalities | musculoskeletal abnormalities | limb abnormalities | neural abnormalities | neural crest abnormalities | renal abnormalities] | respiratory abnormalities | placenta abnormalities | hearing abnormalities | vision abnormalities | twinning | Developmental Origins of Health and Disease | ICD-11
Historic Embryology  
1915 Congenital Cardiac Disease | 1917 Frequency of Anomalies in Human Embryos | 1920 Hydatiform Degeneration Tubal Pregnancy | 1921 Anencephalic Embryo | 1921 Rat and Man | 1966 Congenital Malformations
The Developing Human, 10th edn.jpg Moore, K.L., Persaud, T.V.N. & Torchia, M.G. (2015). The developing human: clinically oriented embryology (10th ed.). Philadelphia: Saunders. UNSW Students have online access to the current 10th edn. through the UNSW Library subscription.
Larsen's human embryology 5th ed.jpg Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone. UNSW Students have online access to the current 5th edn. through the UNSW Library subscription.

Applied Embryology

Australia’s mothers and babies - in brief 2015 (published 2017).


The information is based upon data from the most recent 2017 report "Australia's mothers and babies 2015 - in brief"[9] and earlier reports.[10][11][12][13][14][15][16]

This data should help you as a clinician and researcher to understand the current trends in reproductive medicine within Australia. Also see recent general population data in Australian Statistics.

  • 2015 - 306,725 live births and 2,160 (less than 1%) were stillbirths
  • 2014 - 307,844 live births and 2,200
  • 2013 - 307,277 live births and 2,191
  • 2012 - 312,153 live births and 2,255
  • 2011 - 301,810 live births and 2,220
  • 2009 - 296,791 live births and 2,341
  • 2008 - 294,737 live births and 2,188
  • 2007 - 292,027 live births and 2,177
  • Congenital abnormalities are the leading cause of perinatal deaths (fetal+neonatal)
Australian-births 2011.jpg

Mothers

Mothers - 2015  

304,268 women gave birth in Australia — an increase of 13% since 2005 (267,795 women).

Rate of women giving birth 62 per 1,000 women of reproductive age (15–44 years)

  • rate has declined from a peak of 66 per 1,000 women in 2007.
  • rate has fluctuated between 2005 and 2015

Average age of all women who gave birth continues to rise and was 30.3, compared with 29.7 in 2005.

  • The median age was slightly higher, at 31 years in 2015.

The average age has also increased for Aboriginal and Torres Strait Islander mothers, from 24.9 in 2005 to 25.6 in 2015, with a median of 25 years.

The proportion of mothers aged 35 and over has increased from 20% in 2005 to 22% (See also USA Data)

The proportion of mothers aged under 25 has decreased from 19% to 15%.

The average age of first‐time mothers also increased, from 28.1 in 2005 to 28.9

Multiple pregnancies - represented 1.5% of all pregnancies.

  • Almost all multiple pregnancies (98%) was twinning (dizygotic, monozygotic)
  • Small proportion (2%) were other multiples (triplets, quadruplets or higher).
Maternal Conditions
  • smoking - One in 10 mothers (31,268 or 10%) who gave birth in 2015 smoked at some time during their pregnancy, a decrease from 11% in 2014 and 15% in 2009.
  • hypertension - 8 per 1,000 mothers had chronic hypertension and 37 per 1,000 had gestational hypertension (preeclampsia)
  • maternal diabetes - 11 per 1,000 had pre‐existing diabetes and 94 per 1,000 had gestational diabetes. (2014 - 10 per 1,000 and 83 per 1,000).
Birth - cephalic presentations.jpg

Birth - cephalic presentations

USA mean age of mother 1970- 2010 graph.png

USA mean age of mother (1970-2010)

Babies

Babies  
Gestational Age
  • average gestational age for all babies was 38.6 GA weeks
  • 91 % born at term (37–41 GA weeks)
  • most births occurred in October, September and July

Pre-term Birth

  • 8.6 % born pre‐term (most between 32 and 36 weeks) (8.3 % 2013)
    • 7.9 % NSW (NSW Report NSW Health Statistics)
    • higher in - multiple births, indigenous mothers, smokers, remote areas, very young (under 20) and older mothers (40+)
  • less than 1% born post‐term (42 weeks and over)

USA births by gestational age 1990-2006 graph.png

Birth Weight
  • mean birthweight 3,327 grams
  • 92% (282,530) normal birthweight range
  • 1.4% (4,263) high birthweight (4,500+ grams)
  • 6.5% (19,852) low birthweight (less than 2,500 grams)
    • 81 % stillborn low birthweight
Apgar Score
Apgar score of 7 or more
  • 98% all liveborn babies
  • 92% pre-term babies
  • 92% low birthweight babies (less than 2,500 grams)
  • 1 in 5 liveborn babies require active resuscitation
Special care nurseries (SCN) or neonatal intensive care units (NICU) Admissions
  • 16% (43,348) all Iiveborn babies (2015 - 15%)
  • 74% Pre-term babies
  • majority of multiple births are pre-term
  • 1.5 times more indigenous babies

SCN-NCIU-AUS2015 graph.jpg

Caesarean rates 1990-2014.jpg

Self-Directed Learning 1


2013 National core maternity indicators  
National core maternity indicators 2013.jpg

2013 National core maternity indicators[17]

This report provides a baseline for monitoring changes in the quality of maternity services across Australia using 10 national core maternity indicators.

  1. Smoking in pregnancy for all women giving birth
  2. Antenatal care in the first trimester for all women giving birth
  3. Episiotomy for women having their first baby and giving birth vaginally
  4. Apgar Score of less than 7 at 5 minutes for births at or after term
  5. Induction of labour for selected women giving birth for the first time
  6. Caesarean section for selected women giving birth for the first time
  7. Normal (non-instrumental) vaginal birth for selected women giving birth for the first time
  8. Instrumental vaginal birth for selected women giving birth for the first time
  9. General anaesthetic for women giving birth by caesarean section
  10. Small babies among births at or after 40 weeks gestation
  • National rates have decreased for smoking in pregnancy, episiotomy among women having their first baby and giving birth vaginally and the proportion of babies born weighing less than 2,750 grams at or after 40 weeks.
  • However for some indicators, including induction of labour, caesarean section and instrumental vaginal birth, rates have increased and point to areas for possible further attention.

Unintended Pregnancy

A recent 2018 USA study[18] of Unintended pregnancy and interpregnancy interval by maternal age, National Survey of Family Growth.


  • 40% of pregnancies were unintended
  • 36% followed an interpregnancy interval (IPI) less than 18 months.
  • Within each maternal age group, the percentage of pregnancies that were unintended decreased as IPI increased.


Unintended pregnancy is either mistimed (woman wanted to be pregnant later) or unwanted (did not want to ever be pregnant).


Australian Teenage Pregnancy Statistics (2015) AIHW

Australian teenage mothers and birth rate 2015.jpg

  • Rate of teenage births in Australia is in decline, from 17.5 births per 1,000 women in 2005 to 11.4 in 2015
  • Babies of teenage mothers were 1.3 times as likely to be of low birthweight than babies of 20-24 year old mothers
  • Babies of teenage mothers were 1.2 times as likely to be preterm than babies of 20-24 year old mothers
  • 1 in 4 teenage mothers smoked after 20 weeks of pregnancy


Unintended and Teen Pregnancy  
2001 USA - Approximately one-half of pregnancies in the United States were unintended (Finer 2006, Perspectives on Sexual and Reproductive Health).

An earlier 1995 USA National Survey of Family Growth (NSFG) found:

  • 49% of pregnancies in the USA (excluding miscarriages)
  • 31% of pregnancies resulting in a live birth are unintended
Teen pregnancy USA.png
A recent Canadian retrospective study[19] of half a million births comparing pregnant women < 20 years of age (adolescent) were compared with those of women 20 to 35 years old.
  • Adolescents had a higher rate of smoking and substance use than adult women and were within the lowest education and family income quintiles.
  • Adolescents had a significantly lower risk of gestational hypertension, gestational diabetes, placental abruption, and placenta previa, but their risk of preterm premature rupture of membranes was significantly higher.
  • Neonates with an adolescent mother had significantly higher risks of admission to NICU and very preterm birth.
  • There was no significant difference between the two groups in rates of small for gestational age babies, low birth weight, preterm birth, and fetal death.
Self-Directed Learning 2

Links: CDC Unintended Pregnancy Prevention | Pregnancy Risk Assessment Monitoring System USA | The Measurement and Meaning of Unintended Pregnancy

Assisted Reproduction Technology

Assisted reproductive technology in Australia and New Zealand 2015

Assisted Reproduction Technology (ART) is also sometimes also used to identify In vitro fertilization (IVF) but now includes many new techniques. Assisted reproductive technology (ART) is a group of procedures that involve the in vitro (outside of body) handling of human oocytes (eggs) and sperm or embryos for the purposes of establishing a pregnancy. Each ART treatment involves a number of stages and is generally referred to as an ART treatment cycle. The embryos transferred to a women can either originate from the cycle in which they were created (fresh cycle) or be frozen and thawed before transfer (thaw cycle).

Assisted Reproductive Technology in Australia and New Zealand (2015)[20]

  • 77,721 ART treatment cycles reported from Australian and New Zealand clinics in 2015 (71,479 and 6,242 respectively)
    • 5.6% increase in Australia and 6.0% increase in New Zealand on 2014.
    • 14.4 cycles per 1,000 women of reproductive age (15–44 years) in Australia
    • 94.5% autologous cycles (own oocytes or embryos)
    • 37.4% autologous frozen and thawed
    • 39,006 women who undertook 73,481 autologous fresh and/or thaw cycles
    • Over the last five years there has been an increasing trend in the proportion of cycles where all oocytes or embryos are cryopreserved for potential future use from (2011) 5.0% (2015) 17.2%
  • 35.8 years - average age of women undergoing autologous cycles
    • 40.6 years - average age of women undergoing ART treatment using donor oocytes or embryos
    • 24.8% were aged 40 or older. The average age of the male partner of the women undergoing autologous and recipient cycles was ** 38.1 years - average age of the male partner
  • 22.8% (17,726) resulted in a clinical pregnancy
  • 18.1% (14,040) in a live delivery
    • higher live delivery rate in younger women.
      • under 30 - live delivery rate per embryo transfer 38.4% for autologous fresh cycles and 32.6% for autologous thaw cycles
      • women aged over 44 - live delivery rate was 0.7% per embryo transfer for autologous fresh and 7.6% thaw cycles.
  • 14,791 babies born (including 14,655 liveborn babies)
    • 78.8% were full-term singletons of normal birthweight.
  • shift from cleavage stage transfers to blastocyst transfers (from 57.7% in 2011 to 73.5% in 2015)
  • increase in vitrification as a cryopreservation method (from 73.0% of thaw blastocyst transfer cycles in 2011 to 86.1% in 2015).
  • intracytoplasmic sperm injection (ICSI) has remained stable at around 63% of embryo transfer cycles in 2011-2015.
  • 36% decrease in Multiple births from 6.9% in 2011 to 4.4% in 2015.



Australia 2013 Data
  • 71,516 ART treatment cycles reported from Australian and New Zealand clinics in 2013 (66,143 and 5,373 respectively).
    • 1.9% increase in Australia and 3.8% increase in New Zealand on 2012.
  • 13.7 cycles per 1,000 women of reproductive age (15–44 years) in Australia
    • compared with 5.9 cycles per 1,000 women of reproductive age in New Zealand.
  • 95.1% autologous cycles (womens own oocytes or embryos)
    • 36.6% autologous cycles embryos frozen and thawed.
    • 37,192 women who undertook 67,980 autologous fresh and/or thaw cycles in Australia and New Zealand
  • 1.8 average fresh and/or thaw cycles per woman were undertaken
    • more cycles per woman in Australia (1.9 cycles per woman) than in New Zealand (1.5 cycles per woman).
  • Preimplantation Genetic Diagnosis (PGD) was performed in 2,740 cycles (19.4% increase), 4.4% of cycles in which embryos were created or thawed.
Australia 2012 Data
Assisted reproductive technology in Australia and New Zealand 2012.jpg

The following data from previous year

  • 70,082 assisted reproductive technology (ART) treatment cycles performed in Australia (64,905 ) and New Zealand (5,177),
  • 3,590 babies born (including 13,312 liveborn babies) following ART treatment in 2012.
  • an increase of 5.8% for Australia and a decrease of 0.2% for New Zealand on 2011.
  • 13.7 cycles per 1,000 women of reproductive age (15–44 years) in Australia
  • Women used their own oocytes or embryos (autologous) in 95.2% of treatments, and 34.8% of all cycles used frozen/thawed embryos.
  • 36,171 women who undertook 66,710 autologous fresh and/or thaw cycles in Australia and New Zealand in 2012.
  • average, 1.8 cycles per woman were undertaken in 2012, with more cycles per woman in Australia (1.9 cycles per woman) than in New Zealand (1.5 cycles per woman).
  • increase in cycles where preimplantation genetic diagnosis was performed, from 2.0% of cycles in 2011 to 3.7% of cycles in 2012.
  • Maternal Age
    • women aged under 30, the live delivery rate was 26.0% for both autologous fresh and thaw cycles.
    • women aged over 44, the live delivery rate was 0.9% and 4.6% for autologous fresh and thaw cycles respectively.

Assisted reproductive technology in Australia and New Zealand 2012[21] Nov 2014

USA 2013 Data
ART USA (2013)
  • 6.9 million (11%) of the 61 million women aged 15–44 years had received infertility services at some time in their lives.
  • 93,787 fresh nondonor ART cycles were started in 2013.
  • 33,425 (36%) led to a pregnancy, but only 27,406 (29%) resulted in a live birth.
  • 6,019 (almost 1 in 5) of ART pregnancies did not result in a live birth.


Links: Assisted Reproductive Technology
Self-Directed Learning 3

Early Development Issues

Abnormal Implantation

Ectopic Implantation (Pregnancy)
Ectopic tubal pregnancy
Abnormal implantation sites or Ectopic Pregnancy occurs if implantation is in uterine tube or outside the uterus.
  • sites - external surface of uterus, ovary, bowel, gastrointestinal tract, mesentry, peritoneal wall
  • If not spontaneous then, embryo has to be removed surgically

Tubal pregnancy - 94% of ectopic pregnancies

  • if uterine epithelium is damaged (scarring, pelvic inflammatory disease)
  • if zona pellucida is lost too early, allows premature tubal implantation
  • embryo may develop through early stages, can erode through the uterine horn and reattach within the peritoneal cavity
Ectopic 01.jpg
 ‎‎Ectopic Pregnancy
Page | Play

This is also the most common cause of pregnancy-related deaths in the first trimester. A United Kingdom enquiry into maternal deaths[22], identified ectopic pregnancy as the fourth most common cause of maternal death (73% of early pregnancy deaths).

Hydatidiform Mole

Hydatidiform Mole

Another type of abnormality is when only the conceptus trophoblast layers proliferates and not the embryoblast, no embryo develops, this is called a "hydatidiform mole", which is due to the continuing presence of the trophoblastic layer, this abnormal conceptus can also implant in the uterus. The trophoblast cells will secrete human chorionic gonadotropin (hCG), as in a normal pregnancy, and may appear maternally and by pregnancy test to be "normal". Prenatal diagnosis by ultrasound analysis demonstrates the absence of a embryo.

There are several forms of hydatidiform mole: partial mole, complete mole and persistent gestational trophoblastic tumor. Many of these tumours arise from a haploid sperm fertilizing an egg without a female pronucleus (the alternative form, an embryo without sperm contribution, is called parthenogenesis). The tumour has a "grape-like" placental appearance without enclosed embryo formation. Following a first molar pregnancy, there is approximately a 1% risk of a second molar pregnancy.

This topic is also covered in Placenta - Abnormalities

Twinning

  • Twin deliveries and place of birth in NSW 2001-2005[23] "Both infant and maternal morbidity increase from 39 weeks gestation. Delivery of twins before 36 weeks at smaller hospitals (< 500 deliveries per annum) should be avoided. A twin pregnancy where there is a greater or equal to 20% difference in estimated fetal weights should be considered for referral to a tertiary obstetric unit."

Dizygotic Twinning

Dizygotic twins (fraternal, non-identical) arise from separate fertilization events involving two separate oocyte (egg, ova) and spermatozoa (sperm). Dizygotic twinning can be increased by Assisted Reproductive Technologies (ART) that use double embryo transfer techniques.

Monoygotic Twinning

Monoygotic twins (identical) produced from a single fertilization event (one fertilised egg and a single spermatazoa, form a single zygote), these twins therefore share the same genetic makeup. Occurs in approximately 3-5 per 1000 pregnancies, more commonly with aged mothers. The later the twinning event, the less common are initially separate placental membranes and finally resulting in conjoined twins.

Week Week 1 (GA week 3) Week 2 (GA week 4)
Day 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Cell Number 1 1 2 16 32 128 bilaminar
Event Ovulation Fertilization First cell division Morula Early blastocyst Late blastocyst

Hatching

Implantation starts X inactivation
Follicle 001 icon.jpg Early zygote.jpg Human embryo day 2.jpg Human embryo day 3.jpg Human embryo day 5.jpg CSt3.jpg Week2 001 icon.jpg Macaque Xi at interphase 02.jpg
Monoygotic

Twin Type

Diamniotic

Dichorionic

Diamniotic

Monochorionic

Monoamniotic

Monochorionic

Conjoined

Table based upon recent a recent twinning review.[24]   Links: twinning

Links: Twinning


Self-Directed Learning 4

Abnormal Development

Australian abnormalities by System
Australian abnormalities by System

Embryological development is a robust biological system able to cope with many stresses without long-term consequences. When development does go wrong there are generally 3 major types groups: Genetic (inherited), Environmental (maternal) derived and Unknown (not determined or known) abnormalities. Also often not considered, is that pregnancy itself can also expose abnormalities in the mother (congenital heart disease, diabetes, reproductive disorders) that until the pregnancy had gone undetected.

Genetic abnormalities in medicine are still mainly about determining a family history and good prenatal/neonatal diagnosis. Realise that there exists in all of us genetic variations and some variations which eventually expand be expressed as a genetic disorder (CAG expansions).

Abnormality Links
Abnormality Links: abnormal development | abnormal genetic | abnormal environmental | Unknown | teratogens | ectopic pregnancy | cardiovascular abnormalities | Coelomic Cavity | endocrine abnormalities | gastrointestinal abnormalities | genital abnormalities | head abnormalities | integumentary abnormalities | musculoskeletal abnormalities | limb abnormalities | neural abnormalities | neural crest abnormalities | renal abnormalities] | respiratory abnormalities | placenta abnormalities | hearing abnormalities | vision abnormalities | twinning | Developmental Origins of Health and Disease | ICD-11
Historic Embryology  
1915 Congenital Cardiac Disease | 1917 Frequency of Anomalies in Human Embryos | 1920 Hydatiform Degeneration Tubal Pregnancy | 1921 Anencephalic Embryo | 1921 Rat and Man | 1966 Congenital Malformations

Prenatal diagnosis are the clinical tools used to determine both normal and abnormal development. There are a growing number of new diagnostic techniques that are being applied to human embryonic development.

Prenatal Diagnosis Links
Diagnosis Links: Prenatal Diagnosis | Pregnancy Test | Amniocentesis | Chorionic villus sampling | Ultrasound | Alpha-Fetoprotein | Pregnancy-associated plasma protein-A | Fetal Blood Sampling | Magnetic Resonance Imaging | Computed Tomography | Non-Invasive Prenatal Testing | Fetal Cells in Maternal Blood | Preimplantation Genetic Screening | Comparative Genomic Hybridization | Genome Sequencing | Neonatal Diagnosis | Category:Prenatal Diagnosis | Fetal Surgery | Classification of Diseases | Category:Neonatal Diagnosis
NIPT - Non-Invasive Prenatal Testing
Fetal aneuploidy screening with cell-free DNA in late gestation[25]"The aim of this study was to evaluate clinical use of NIPT at gestational ages of 23 weeks and above. A cohort of 5579 clinical patients with singleton gestations of 23 weeks or greater submitting a blood sample for NIPT in an 18-month period were selected for this study. ...Of 5372 reported late-gestation samples, 151 (2.8%) were reported as aneuploidy detected or suspected. In late-gestation samples, the overall observed positive predictive value (PPV) for NIPT was 64.7%, with an observed PPV of 100% in the subset of cases with multiple clinical indications including abnormal ultrasound findings. NIPT is a highly accurate prenatal screening option for women after 23 weeks of gestation. Women who presented for NIPT in the latter stages of pregnancy more frequently specified clinical indications of abnormal ultrasound findings than women who entered screening earlier in pregnancy."

More? Fetal Cells in Maternal Blood | RACGP | NCHPEG

While genetic abnormalities will have well-defined impacts upon development, environmentally derived effects can be harder to define and often variable depending on many different factors (timing, exposure level, and the combination effects with other factors). This combination effect can also be seen between genetic and environmental interacting to give an even broader spectrum of both major and minor abnormalities.

Environmental Links
Environmental Links: Introduction | low folic acid | iodine deficiency | Nutrition | Drugs | Australian Drug Categories | USA Drug Categories | thalidomide | herbal drugs | Illegal Drugs | smoking | Fetal Alcohol Syndrome | TORCH | viral infection | bacterial infection | fungal infection | Zoonotic Infection | Toxoplasmosis | Malaria | Maternal Diabetes | Maternal Hypertension | maternal hyperthermia | Maternal Inflammation | Maternal Obesity | Hypoxia | Biological Toxins | Chemicals | heavy metals | radiation | Prenatal Diagnosis | Neonatal Diagnosis | International Classification of Diseases | Fetal Origins Hypothesis
Bacterial Links: bacterial infection | syphilis | gonorrhea | tuberculosis | listeria | salmonella | TORCH | Environmental | Category:Bacteria
Viral Links: viral infection | TORCH | cytomegalovirus | Hepatitis Virus | HIV | Parvovirus | Polio Virus | rubella virus | Chickenpox | Lymphocytic Choriomeningitis Virus | Zika Virus | rotavirus | vaccination | Environmental
Historic Embryology - Viral 
1941 Rubella Cataracts | 1944 Rubella Defects

International Classification of Diseases

The International Classification of Diseases (ICD) World Health Organization's classification used worldwide as the standard diagnostic tool for epidemiology, health management and clinical purposes. This includes the analysis of the general health situation of population groups. It is used to monitor the incidence and prevalence of diseases and other health problems. Within this classification "congenital malformations, deformations and chromosomal abnormalities" are (Q00-Q99) but excludes "inborn errors of metabolism" (E70-E90).


ICD-10

Australian Birth Anomalies System

"The national collation and reporting of birth anomalies data has been suspended in recent years due to concerns about data quality and comparability."
  • Variability among states and territories in scope of birth anomalies data collections: sources of birth anomalies notifications and definitions and classifications used; method of data collection and available resources.
  • Variability among the states and territories in the timing and method of the provision of birth anomalies data to the AIHW National Perinatal Statistics Unit (NPSU) for national collation and reporting.
  • New Australian Birth Anomalies System should be data for birth anomalies detected up to 1 year of age
    • including data on terminations of pregnancies with birth anomalies and regardless of gestational age (i.e. including less than 20 weeks gestation)
  • System will initially be based on data from the states able to detect birth anomalies at least up to 1 year of age (NSW, VIC, WA and SA), further extending the period of detection in the future.
  • Congenital anomalies are coded using the British Paediatric Association Classification of Diseases (ICD-9-BPA), based on the International Classification of Diseases, 9th Revision (ICD-9).
The Australian Congenital Anomalies Monitoring System (ACAMS) supersedes the National Congenital Malformations and Birth Defects Data Collection (NCM&BD).
Congenital Anomalies in Australia 2002-2003  
Congenital anomalies in Australia 2002-2003[26] was published in 2008 as part a new revised series on 33 selected congenital anomalies also monitored internationally by the International Clearinghouse of Birth Defects Surveillance and Research.
  • Hypospadia is the most commonly reported condition at birth, but severity of the condition is not reported to the national data collection.
  • Trisomy 21 (Down’s syndrome) is the next most commonly reported condition at birth (11.1 per 10,000 births), but many affected pregnancies are detected early and managed by early termination. An estimated 63.6% of the fetuses diagnosed with trisomy 21 were managed by terminations of pregnancy or were fetal deaths. When terminations of pregnancy were included, the estimated rate for trisomy 21 was 26.3 per 10,000 pregnancies. Trisomy 21 was more common with advancing maternal age.
    • Other chromosomal abnormalities such as trisomy 13 and trisomy 18 also had a large proportion of fetal deaths or terminations of pregnancy and were more common in women aged 40 years or older.
  • Neural tube defects were diagnosed in about 4.2 per 10,000 births.
  • More males than females diagnosed with congenital anomalies for many of the reported conditions (e.g. hydrocephalus, most of the reported congenital heart diseases, oesophageal atresia and polycystic kidneys).
  • Anencephaly - younger women had a higher rate compared with older women, most of the women who gave birth to a baby with anencephaly (77.2%) were in the 20–34 years age group.
Links: Human Abnormal Development | Hypospadia | Trisomy 21 | Trisomy 13 Trisomy 18 | Neural Tube Defects | Folic Acid and Neural Tube Defects | Hydrocephalus | Cardiovascular Abnormalities | Polycystic Kidney Disease | Anencephaly | Australian Statistics | Reports
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
External Links: AIHW Report Page | NPESU Report Page | International Clearinghouse of Birth Defects Surveillance and Research

Links: Australian Congenital Anomalies Monitoring System | Congenital Anomalies in Australia 2002-2003

NSW Data

Congenital Conditions Register

Scheduled congenital conditions (section 2) detected during pregnancy or in infants up to one year of age in NSW are required to be reported under the NSW Public Health Act 1991.

Scheduled congenital conditions include:

  1. All structural malformations. Examples include spina bifida, microcephaly, transposition of the great vessels, ventricular septal defects, pulmonary agenesis, polycystic lungs, duodenal atresia, exomphalos, hypospadias, cleft lip/palate, microphthalmia, limb reductions, polydactyly, birthmarks greater than 4 cms diameter, cystic hygroma and multisystem syndromes including at least one structural malformation.
  2. Chromosomal abnormalities. Examples include Down syndrome and unbalanced translocations.
  3. Four medical conditions: cystic fibrosis, phenylketonuria, congenital hypothyroidism and thalassaemia major.

Congenital conditions that are not notifiable include:

  1. Minor anomalies occurring in isolation (Examples of minor anomalies include skin tags, deviated nasal septum, tongue tie, benign heart murmurs, clicky non-dislocating hips, sacral dimples, positional talipes, abnormal palmar creases, dysmorphic features).
  2. Birth injuries.
  3. Congenital infections which do not result in a structural malformation.
  4. Tumours and cysts.
  5. Conditions arising from prematurity or asphyxiation.


Links: NSW Health - Congenital Conditions Register - Reporting Requirements 2012 | PDF


NSW Mothers and Babies Report 2015

New South Wales Mothers and Babies 2015 cover
New South Wales Mothers and Babies 2015
NSW Perinatal Data Collection form
NSW Perinatal Data Collection form

NSW is one of the largest states in Australia by population. The New South Wales Perinatal Data Collection (PDC) is a population-based surveillance system covering all births in NSW public and private hospitals, as well as home births. It encompasses all live births, and stillbirths of at least 20 weeks gestation or at least 400 grams birth weight.[27]

  • Number of births decreased from 97,245 in 2011 to 96,391 in 2015 (decrease of 0.9%).
  • Percentage of teenage mothers fell from 3.2% in 2011 to 2.5% in 2015.
  • Rate of normal vaginal birth decreased from 56.9% in 2011 to 56.0% in 2015.
  • Operative and instrumental births were more common among privately than publicly insured mothers.
  • Proportion of smoking mothers during pregnancy declined from 11.1% in 2011 to 8.9% in 2015.
  • Majority of mothers planned to give birth in a hospital labour ward
    • 87% per cent of mothers who planned to give birth in a birth centre actually did so.
    • There were 187 homebirths in NSW reported in 2015.
  • Premature babies (less than 37 weeks gestation) 7.9% (slight increase from 7.5% in 2011).
  • Since 2011, the rate of low birth weight (less than 2,500 grams) has remained stable, ranging from 6.1% to 6.6%.
    • Low birth weight rate was 6.6% in 2015.
  • Between 2011 and 2015, the reported number of Aboriginal or Torres Strait Islander mothers giving birth increased from 2,975 to 3,823, an increase from 3.1% to 4.0% of all mothers.
  • Aboriginal or Torres Strait Islander
    • teenage mothers fell from 19.0% in 2011 to 15.4% in 2015.
    • 45.0% of Aboriginal or Torres Strait Islander mothers reported smoking during pregnancy.
    • Since 2011, rates of low birth weight and prematurity in Aboriginal or Torres Strait Islander babies has been over 11%. In 2015, 11.3% of Aboriginal or Torres Strait Islander babies were low birth weight and 12.7% were premature.
    • Perinatal mortality rate of 9.6 per 1,000 births in Aboriginal or Torres Strait Islander mothers in 2015 is higher than the rate of 8.1 per 1,000 births experienced among babies born to non-Aboriginal or Torres Strait Islander mothers.


Victoria - 10 most reported birth anomalies  
Based upon statistics from the Victorian Perinatal Data Collection Unit in Victoria between 2003-2004.
Hypospadia hypospadias (More? External Genital Male Development Movie)
Obstructive Defect of the Renal Pelvis Obstructive Defects of the Renal Pelvis (obstructive defects of the renal pelvis, uteropelvic junction obstruction, pelvo-uterero junction obstruction) Term describing a developmental renal abnormality due to partial or complete blockage of the drainage of the kidney pelvis requiring surgical correction. The blockage can also have several causes including: unusual ureter twisting or bending, ureter compression by a blood vessel, malformations of the muscular wall. The blockage leads to an accumulation of urine in the affected region, with several potential effects: nephron damage from compression (hydronephrosis); decreased urine output leading to lack of amniotic fluid (oligohydramnios); respiratory development effects due to the lack of amniotic fluid.
  • The most common type of obstruction is at the uteropelvic junction (UPJ), between the junction of the ureter and the kidney.
  • Blockage lower as the ureter enters the bladder, the ureterovesicular junction (UVJ), usually involves only one kidney and the back flow enlarges the affected ureter (megaureter).

(More? renal abnormalities | renal)

Ventricular Septal Defect ventricular septal defect (More? ventricular septal defect)

Basic Heart Development Timeline.jpg

Heart Development Timeline (see Basic Cardiac Embryology)

Congenital dislocation hip Developmental dysplasia of the hip or Congenital Dislocated Hip

(Developmental dysplasia of the hip (DDH), congenital hip dislocation, congenital hip dysplasia) Term describes a spectrum of musculoskeletal disorders of hip instability due either to the femoral head being able to move outside the acetabulum (luxation or dislocation), or abnormally within the acetabulum (subluxation or partial dislocation). This includes presentation following a normal examination of the hips in the newborn period (Ortolani and Barlow tests). When detected can be managed with splinting (Denis-Browne splint) allows the hip joint to develop normally and does not require surgery. If undetected and left untreated, the hip joint develops abnormally and surgical reduction is required. (More? Pelvis Development)

Trisomy 21 male Trisomy 21 or Down syndrome - The most common genetic abnormality. (More? Trisomy 21)
Hydrocephalus MRI hydrocephalus rapid increase in head circumference or an unusually large head size due to excessive accumulation of cerebrospinal fluid in the brain.(More? hydrocephalus | Neural Abnormalities | NINDS - Hydrocephalus Fact Sheet | Hydrocephalus Support Association | USA National Hydrocephalus Foundation)
Cleft palate cleft palate - The palate separates the nasal cavity from the oral cavity, the abnormality has many different causes, and occurs more frequently in females (57%) than in males (43%). (More? cleft palate)
Trisomy 18 male Trisomy 18 or Edward Syndrome - multiple abnormalities of the heart, diaphragm, lungs, kidneys, ureters and palate 86% discontinued (More? Trisomy 18)
Renal Agenesis/Dysgenesis - reduction in neonatal death and stillbirth since 1993 may be due to the more severe cases being identified in utero and being represented amongst the increased proportion of terminations (approximately 31%). (More? Renal Abnormalities - Renal Agenesis)
Bilateral cleft palate cleft lip and palate - occur with another defect in 33.7% of cases.(More? cleft lip and palate)
Links: Human Abnormal Development | Australian Statistics | Victoria 2004 | USA 2006 | Europe 2010
USA Statistics
USA Selected Abnormalities (CDC National estimates for 21 selected major birth defects 2004–2006)  
Birth Defects Cases per Births (1 in ...) Estimated Annual Number of Cases
Anencephaly 4,859 859
Spina bifida without anencephaly 2,858 1,460
Encephalocele 12,235 341
Anophthalmia/microphthalmia 5,349 780
Common truncus 13,876 301
Transposition of great arteries 3,333 1,252
Tetralogy of Fallot 2,518 1,657
Atrioventricular septal defect 2,122 1,966
Hypoplastic left heart syndrome 4,344 960
Cleft palate without cleft lip 1,574 2,651
Cleft lip with and without cleft palate 940 4,437
Esophageal atresia/tracheoesophageal fistula 4,608 905
Rectal and large intestinal atresia/stenosis 2,138 1,952
Reduction deformity, upper limbs 2,869 1,454
Reduction deformity, lower limbs 5,949 701
Gastroschisis 2,229 1,871
Omphalocele 5,386 775
Diaphragmatic hernia 3,836 1,088
Trisomy 13 7,906 528
Trisomy 21 (Down syndrome) 691 6,037
Trisomy 18 3,762 1,109
Links: Human Abnormal Development | CDC Birth Defects - Data & Statistics | USA Statistics | Victoria 2004 | USA 2006 | Europe 2010
European Statistics
Malformation (non-chromosomal) Total Cases Cases Prenatally Diagnosed  % of Total Cases
All Anomalies 75751 22573 30
Anencephalus and similar 1232 1185 96
Spina Bifida 1577 1288 82
Hydrocephalus 1914 1403 73
Transposition of great vessels 1188 454 38
Hypoplastic left heart 888 624 70
Cleft lip with or without palate 2857 1379 48
Diaphragmatic hernia 893 509 57
Gastroschisis 993 904 91
Omphalocele 730 596 82
Bilateral renal agenesis including Potter syndrome 392 343 88
Posterior urethral valve and/or prune belly 291 234 80
Limb reduction 1626 811 50
Club foot - talipes equinovarus 3678 1398 38
Malformation (chromosomal)
Chromosomal 12479 8765 70
Down Syndrome 7233 4538 63
Patau syndrome/trisomy 13 685 625 91
Edwards syndrome/trisomy 18 1709 1537 90
Data: EUROCAT Website Database data uploaded 04/12/2012
Links: Human Abnormal Development | Australian Statistics | Victoria 2004 | USA 2006 | Europe 2010


Genetic

Links: Abnormal Development - Genetic
Self-Directed Learning 5

Teratology

Prenatal Screening

Amniocentesis

How and why do things go wrong in development?

These notes cover abnormalities that can occur during development often described as congenital defects or birth defects. There are many different ways that developmental abnormalities can occur the 3 major types are Genetic (inherited), Environmental (maternal) and Unknown (not determined) derived abnormalities. The environmental factors that cause or lead to any of these abnormalities are described as Teratogens.

Diagnosis Links: Prenatal Diagnosis | Pregnancy Test | Amniocentesis | Chorionic villus sampling | Ultrasound | Alpha-Fetoprotein | Pregnancy-associated plasma protein-A | Fetal Blood Sampling | Magnetic Resonance Imaging | Computed Tomography | Non-Invasive Prenatal Testing | Fetal Cells in Maternal Blood | Preimplantation Genetic Screening | Comparative Genomic Hybridization | Genome Sequencing | Neonatal Diagnosis | Category:Prenatal Diagnosis | Fetal Surgery | Classification of Diseases | Category:Neonatal Diagnosis
Ultrasound
Ultrasound
Ectopic 01.jpg
 ‎‎Ectopic Pregnancy
Page | Play
Cleft lip 01.jpg
 ‎‎Cleft Lip 18 Week
Page | Play
Cleft lip 02.jpg
 ‎‎Cleft Lip 15 Week
Page | Play
Gastroschisis 01.jpg
 ‎‎Gastroschisis
Page | Play

Now consider the terms used to describe the different environmental effects that can occur during pregnancy that may influence outcomes.

  • Teratogen (Greek, teraton = monster) any agent that causes a structural abnormality (congenital abnormalities) following fetal exposure during pregnancy. The overall effect depends on dosage and time of exposure.
  • Absolute risk the rate of occurrence of an abnormal phenotype among individuals exposed to the agent. (e.g. fetal alcohol syndrome)
  • Relative risk the ratio of the rate of the condition among the exposed and the nonexposed. (e.g. smokers risk of having a low birth weight baby compared to non-smokers) A high relative risk may indicate a low absolute risk if the condition is rare.
  • Mutagen a chemical or agent that can cause permanent damage to the deoxyribonucleic acid (DNA) in a cell. DNA damage in the human egg or sperm may lead to reduced fertility, spontaneous abortion (miscarriage), birth defects and heritable diseases.
  • Fetotoxicant is a chemical that adversely affects the developing fetus, resulting in low birth weight, symptoms of poisoning at birth or stillbirth (fetus dies before it is born).
  • Synergism when the combined effect of exposure to more than one chemical at one time, or to a chemical in combination with other hazards (heat, radiation, infection) results in effects of such exposure to be greater than the sum of the individual effects of each hazard by itself.
  • Toxicogenomics the interaction between the genome, chemicals in the environment, and disease. Cells exposed to a stress, drug or toxicant respond by altering the pattern of expression of genes within their chromosomes. Based on new genetic and microarray technologies.

Teratogens

  • Infections, collectively grouped under the acronym TORCH for Toxoplasmosis, Other organisms (parvovirus, HIV, Epstein-Barr, herpes 6 and 8, varicella, syphilis, enterovirus) , Rubella, Cytomegalovirus and Hepatitis. See also the related topics on maternal hyperthermia and bacterial infections. (More? Postnatal Immunisation)
  • Maternal diet the best characterised is the role of low folic acid and Neural Tube Defects (NTDs) see also abnormal neural development and Neural Tube Defects (NTDs). More recently the focus has been on dietary iodine levels and the role they also play on neural development.
  • Maternal drugs effects either prescription drugs (therapeutic chemicals/agents, thalidomide limb development), non-prescription drugs (smoking), and illegal drugs (Cannabis/Marijuana, Methamphetamine/Amphetamine, Cocaine, Heroin, Lysergic Acid Diethylamide)
  • Environment (smoking, chemicals, heavy metals, radiation) and maternal endocrine function (maternal diabetes, thyroid development) and maternal stress.
  • Teratogen synergism, different environmental effects can act individually or in combination on the same developing system. For example, neural development can be impacted upon by alcohol (fetal alcohol syndrome), viral infection (rubella) and/or inadequate dietry folate intake (neural tube defects). These effects may also not be seen as a direct effect on a system or systems but result in a reduced birth weight and the potential postnatal developmental effects. Consider also this in relation to the increasing support to the fetal origins hypothesis.
  • Alcohol - In utero alcohol effects on foetal, neonatal and childhood lung disease.[28]


Links:

Abnormality Links: abnormal development | abnormal genetic | abnormal environmental | Unknown | teratogens | ectopic pregnancy | cardiovascular abnormalities | Coelomic Cavity | endocrine abnormalities | gastrointestinal abnormalities | genital abnormalities | head abnormalities | integumentary abnormalities | musculoskeletal abnormalities | limb abnormalities | neural abnormalities | neural crest abnormalities | renal abnormalities] | respiratory abnormalities | placenta abnormalities | hearing abnormalities | vision abnormalities | twinning | Developmental Origins of Health and Disease | ICD-11
Historic Embryology  
1915 Congenital Cardiac Disease | 1917 Frequency of Anomalies in Human Embryos | 1920 Hydatiform Degeneration Tubal Pregnancy | 1921 Anencephalic Embryo | 1921 Rat and Man | 1966 Congenital Malformations
Environmental Links: Introduction | low folic acid | iodine deficiency | Nutrition | Drugs | Australian Drug Categories | USA Drug Categories | thalidomide | herbal drugs | Illegal Drugs | smoking | Fetal Alcohol Syndrome | TORCH | viral infection | bacterial infection | fungal infection | Zoonotic Infection | Toxoplasmosis | Malaria | Maternal Diabetes | Maternal Hypertension | maternal hyperthermia | Maternal Inflammation | Maternal Obesity | Hypoxia | Biological Toxins | Chemicals | heavy metals | radiation | Prenatal Diagnosis | Neonatal Diagnosis | International Classification of Diseases | Fetal Origins Hypothesis
Genetic Links: genetic abnormalities | maternal age | Trisomy 21 | Trisomy 18 | Trisomy 13 | Trisomy X | Monosomy | Fragile X | Williams | Alagille | Philadelphia chromosome | mitochondria | hydatidiform mole | epigenetics | Prenatal Diagnosis | Neonatal Diagnosis | meiosis | mitosis | International Classification of Diseases | genetics

Critical Periods of Development

Human critical periods of development
  • Finally, when studying this topic remember the concept of critical periods of development that will affect the overall impact of the above listed factors. This can be extended to the potential differences between prenatal and postnatal effects, for example with infections and outcomes.


Critical Periods of Human Development
Conceptus Embryonic development (weeks) Fetal period (weeks)
1
2
3
4
5
6
7
8
9
16
20-36
38
Early zygote.jpg Week2 001 icon.jpg Stage9 sem4c.jpg Stage13 sem1c.jpg Stage15 bf1c.jpg Stage17 bf1c.jpg Stage19 bf1c.jpg Stage23 bf1c.jpg
Neural
Stage2.jpg Heart
Upper limbs
Lower limbs
Ear
Eye
CSt3.jpg Palate
Teeth
Week2 001 icon.jpg External genitalia
Loss Major abnormalities Functional and Minor abnormalities


Self-Directed Learning 6

Links: Embryonic Development | Timeline human development | Movie - Human Development annotated cartoon | Human - critical periods


Australian Drug Categories

Legal drugs are classified, usually by each country's appropriate regulatory body, on the safety of drugs during pregnancy. In Australia, the Therapeutic Goods Authority has classes (A, B1, B2, B3, C, D and X) to define their safety. (More? Australian Drug Categories) In the USA, since 2015 drugs are classified by the Food and Drug Administration (FDA) into new classes to define their safety. The Australian categorisation of medicines for use in pregnancy does not follow a hierarchical structure.

  • Human data are lacking or inadequate for drugs in the B1, B2 and B3 categories
  • Subcategorisation of the B category is based on animal data
  • The allocation of a B category does not imply greater safety than a C category
  • Medicines in category D are not absolutely contraindicated during pregnancy (e.g.anticonvulsants)


  • Pregnancy Category A - Have been taken by a large number of pregnant women and women of childbearing age without an increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.
  • Pregnancy Category B1 - Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.
  • Pregnancy Category B2 - Have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.
  • Pregnancy Category B3 - Have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
  • Pregnancy Category C - Have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible.
  • Pregnancy Category D - Have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects.
  • Pregnancy Category X - Have such a high risk of causing permanent damage to the fetus that they should NOT be used in pregnancy or when there is a possibility of pregnancy.


US FDA - 2015 Pregnancy and Lactation Labeling (Drugs) 2015  
FDA drug category changes 2015.jpg
Since 2015 the labelling classes (A, B, C, D, and X) have been replaced with the new "FDA Pregnancy and Lactation Labeling Rule" (PLLR).
Links: USA Drug Categories | Pregnancy and Lactation Labeling (Drugs) Final Rule

Infant Drug Clearance

Drug clearance rates

The drug clearance data below are only approximate calculated rates for the fetus and infant from NZ Drug Safety in Lactation

Post-conceptual Age (weeks) Clearance of Drug (percentage of adults)
24-28 5%
28-34 10%
34-40 33%
40-44 50%
44-68 66%
> 68 100%


Links: Abnormal Development - Drugs | Australian Fetal Risk Categories | USA FDA Fetal Risk Categories | Therapeutic Goods Authority | Australian Drug Evaluation Committee (ADEC) | TGA - Medicines Pregnancy Database | Appendix A: Therapeutic goods exempted from pregnancy classification | NSW Poisons Information Centre


Self-Directed Learning 7

References

  1. Department of Health (2018) Clinical Practice Guidelines: Pregnancy Care. Canberra: Australian Government Department of Health. (8 October 2018 - Update)
  2. Miller JE, Wu C, Pedersen LH, de Klerk N, Olsen J & Burgner DP. (2018). Maternal antibiotic exposure during pregnancy and hospitalization with infection in offspring: a population-based cohort study. Int J Epidemiol , , . PMID: 29415232 DOI.
  3. AIHW 2017. Incidence of insulin-treated diabetes in Australia, 2015. Diabetes series no. 27. Cat. no. CVD 78. Canberra: AIHW. Viewed 20 February 2017 http://www.aihw.gov.au/publication-detail/?id=60129558632.
  4. Chiba ME, Saito M, Suzuki N, Honda Y & Yaegashi N. (2003). Measles infection in pregnancy. J. Infect. , 47, 40-4. PMID: 12850161
  5. AIHW 2016. Monitoring the health impacts of mandatory folic acid and iodine fortification 2016. Cat. no. PHE 208. Canberra: AIHW. PDF
  6. Pyke AT, Daly MT, Cameron JN, Moore PR, Taylor CT, Hewitson GR, Humphreys JL & Gair R. (2014). Imported zika virus infection from the cook islands into australia, 2014. PLoS Curr , 6, . PMID: 24944843 DOI.
  7. Hamel R, Dejarnac O, Wichit S, Ekchariyawat P, Neyret A, Luplertlop N, Perera-Lecoin M, Surasombatpattana P, Talignani L, Thomas F, Cao-Lormeau VM, Choumet V, Briant L, Desprès P, Amara A, Yssel H & Missé D. (2015). Biology of Zika Virus Infection in Human Skin Cells. J. Virol. , 89, 8880-96. PMID: 26085147 DOI.
  8. Besnard M, Lastere S, Teissier A, Cao-Lormeau V & Musso D. (2014). Evidence of perinatal transmission of Zika virus, French Polynesia, December 2013 and February 2014. Euro Surveill. , 19, . PMID: 24721538
  9. Australian Institute of Health and Welfare 2017. Australia’s mothers and babies 2015—in brief. Perinatal statistics series no. 33. Cat no. PER 91. Canberra: AIHW.
  10. AIHW 2016. Australia's mothers and babies 2014—in brief. Perinatal statistics series no. 32. [ http://www.aihw.gov.au/publication-detail/?id=60129557656 Cat. no. PER 87]. Canberra: AIHW.
  11. AIHW 2015. Australia's mothers and babies 2013 - in brief. Perinatal statistics series no. 31. Cat. no. PER 72. Canberra: AIHW. PDF Viewed 13 December 2015. http://www.aihw.gov.au/publication-detail/?id=60129553770
  12. Hilder L, Zhichao Z, Parker M, Jahan S, Chambers GM 2014. Australia’s mothers and babies 2012. Perinatal statistics series no. 30. Cat. no. PER 69. Canberra: AIHW. Viewed 16 December 2014. http://www.aihw.gov.au/publication-detail/?id=60129550033
  13. Li Z, Zeki R, Hilder L & Sullivan EA 2013. Australia’s mothers and babies 2011. Perinatal statistics series no. 28. Cat. no. PER 59. Canberra: AIHW.
  14. Li Z, McNally L, Hilder L & Sullivan EA 2011. Australia's mothers and babies 2009 AIHW Perinatal statistics series no. 25 Cat. no. PER 52. Sydney: AIHW National Perinatal Epidemiology and Statistics Unit.
  15. Laws P & Sullivan EA 2010 Australia's mothers and babies 2008 AIHW Perinatal statistics series no. 24 Cat. no. PER 48. Sydney: AIHW National Perinatal Statistics Unit.
  16. Laws P & Sullivan EA 2009. Australia's mothers and babies 2007 AIHW Perinatal statistics series no. 23 Cat. no. PER 48. Sydney: AIHW National Perinatal Statistics Unit.
  17. AIHW National Perinatal Epidemiology and Statistics Unit and AIHW 2013. National core maternity indicators. Cat. no. PER 58. Canberra: AIHW.
  18. Ahrens KA, Thoma M, Copen C, Frederiksen B, Decker E & Moskosky S. (2018). Unintended pregnancy and interpregnancy interval by maternal age, National Survey of Family Growth. Contraception , , . PMID: 29501647 DOI.
  19. Fleming N, Ng N, Osborne C, Biederman S, Yasseen AS, Dy J, Rennicks White R & Walker M. (2013). Adolescent pregnancy outcomes in the province of Ontario: a cohort study. J Obstet Gynaecol Can , 35, 234-245. PMID: 23470111 DOI.
  20. Fitzgerald O, Harris K, Paul RC, Chambers GM. (2017) Assisted reproductive technology in Australia and New Zealand 2015. Sydney: National Perinatal Epidemiology and Statistics Unit, the University of New South Wales Sydney.
  21. Macaldowie A, Wang YA, Chughtai AA & Chambers GM 2014. Assisted reproductive technology in Australia and New Zealand 2012. Sydney: National Perinatal Epidemiology and Statistics Unit, the University of New South Wales. PDF
  22. Confidential Enquiry into Maternal Deaths (CEMD) Why Mothers Die 2000–2002 PDFPDF2
  23. Algert CS, Morris JM, Bowen JR, Giles W & Roberts CL. (2009). Twin deliveries and place of birth in NSW 2001-2005. Aust N Z J Obstet Gynaecol , 49, 461-6. PMID: 19780726 DOI.
  24. Hall JG. (2003). Twinning. Lancet , 362, 735-43. PMID: 12957099 DOI.
  25. Taneja PA, Prosen TL, de Feo E, Kruglyak KM, Halks-Miller M, Curnow KJ & Bhatt S. (2017). Fetal aneuploidy screening with cell-free DNA in late gestation. J. Matern. Fetal. Neonatal. Med. , 30, 338-342. PMID: 27124739 DOI.
  26. Abeywardana S & Sullivan EA 2008. Congenital anomalies in Australia 2002–2003. Birth anomalies series no. 3 Cat. no. PER 41. Sydney: AIHW National Perinatal Statistics Unit.
  27. Centre for Epidemiology and Evidence. New South Wales Mothers and Babies 2015. Sydney: NSW Ministry of Health, 2016.
  28. Gauthier TW & Brown LA. (2017). In utero alcohol effects on foetal, neonatal and childhood lung disease. Paediatr Respir Rev , 21, 34-37. PMID: 27613232 DOI.

Links

The following are links to relevant notes pages that cover the key embryology concepts in this tutorial. These pages and their links will provide further detailed information.

Applied Embryology

Timeline human development | Fetal Development | Birth | Apgar test | Neonatal Development | Week 2 Abnormalities - Trophoblastic Disease | Placenta Development | Neural Abnormalities | Abnormal Development - Folic Acid and Neural Tube Defects | Week 3 | Cardiovascular Abnormalities | Twinning | Blastocyst | Molecular Development

Teratology Links

Human Abnormal Development | Genetic Abnormalities | Environmental Factors | Drugs | Trisomy 21 (Down Syndrome) | Fetal Alcohol Syndrome | Viral Infection | Rubella Virus | Hyperthermia

Self-Directed Learning

Self-Directed Learning 1 - Australian Statistics
Once you have thought about the Australian statistics, now look at the latest report summary Australia’s mothers and babies 2012 and Australian Statistics.
  • What are the current trends in Australia?
  • What factors may be contributing to these changes?
  • Are there any long-term trends in birth statistics?
  • What does this mean for future health care provision?


Self-Directed Learning 2 - Pregnancy
  • What indications would prompt a woman to take a pregnancy test?
  • What test are available and where is test information provided?
  • How much do these tests cost?
  • When does a doctor become involved and what issues should be discussed?


Self-Directed Learning 3 - Assisted Reproductive Technologies
  • Why is this more than "in vitro fertilization"?
  • How many different Assisted Reproductive Technologies are available in Australia?
  • How has the change from DET to SET impacted on reproductive outcomes?
  • What other clinical issues should be considered when discussing ART?
  • What preimplantation genetic tests are currently available?


Self-Directed Learning 4 - The First Few Weeks
  • After fertilization, when does initial implantation occur?
  • Which hormone maintains the initial pregnacy, where is it from and how does it act?
  • How would an ectopic pregnancy differ at this stage?
  • What additional maternal issues should be considered for multiple pregnancies?


Self-Directed Learning 5 - Abnormal Development
  • What are the 3 major forms of abnormal development?
  • What are the main chromosomal abnormalities and how do they occur?
  • How are congenital abnormalities reported and classified within Australia?


Self-Directed Learning 6 - Prenatal Diagnosis
  • What maternal lifestyle issues should be considered for a pregnancy?
  • What diagnostic techniques are currently available and in development?
  • What can ultrasound normally identify?


Self-Directed Learning 7 - Medications in Pregnancy
  • How does drug classification differ between countries?
  • Do european and asian countries apply the same drug classification system(s)?
  • How are teratogens identified?
  • Why does fetal drug clearance differ from maternal clearance?

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Cite this page: Hill, M.A. (2018, October 19) Embryology BGD Tutorial - Applied Embryology and Teratology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGD_Tutorial_-_Applied_Embryology_and_Teratology

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© Dr Mark Hill 2018, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G