This Phase 2 Medical 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.
Subsequently, only a brief coverage can be given of any one topic. You should come back and look later at the online resources for more detailed descriptions.
Applied Embryology: timeline of development, birth statistics, abnormalities statistics, unwanted pregnancies, trophoblastic disease, embryonic development, placenta, fetal development, folic acid, multiple pregnancies.
Teratology: definitions, critical periods, medications, chromosomal abnormalities, environmental factors, infection
Textbook Reading: Human Embryology, WJ. Larsen; The Developing Human: Clinically Oriented Embryology. Moore & Persaud
Tutorial Handout: Tutorial – Applied Embryology and Teratogenicity (8 pages, PDF document)
Page Links: Introduction | Timeline of Human Development | Critical Periods of Development | Applied Embryology | Unwanted Pregnancy | Assisted Reproduction Technology | Australian Birth Anomalies System | Abnormal Development | Teratology | FDA Fetal Risk Categories | Applied Embryology Links | Teratology Links | Additional Abnormal Development Links | WWW Links | Glossary |
The data below are highlights from the AIHW National Perinatal Statistics Unit recent annual publication: "Australia's mothers and babies 2005"
Australia's mothers and babies 2005
267,793 women gave birth to 272,419 babies in Australia.
15,214 more births (5.9%) than reported in 2004.
Mothers
29.8 years was the mean maternal age, continuing an upward trend. (More? Australian Statistics | Australian Maternal Statistics)
9,867 were of Aboriginal or Torres Strait Islander origin, making up 3.7% of all mothers.
17.4% reported smoking at all during pregnancy. (More? Smoking)
58.5% had a spontaneous vaginal birth (0.4% vaginal breech birth, 3.5% forceps and 7.2% vacuum extractions). (More? Birth Overview)
30.3% gave birth by caesarean section (19.5% in 1996) (More? Caesarean Delivery)
83.2% had previously had a caesarean section
1.7% had a multiple pregnancy (More? Twinning)
3.0 days median length of stay in hospital (caesarean section 5.0 days)
Babies
8.1% were preterm (less than 37 weeks gestation)
6.4% of liveborn babies were of low birthweight (less than 2,500 grams) (More? Low Birth Weight | Fetal Origins Hypothesis)
105.5 male / 100 female live births
15.5% of liveborn babies admitted to a special care nursery or neonatal intensive care unit.
6,044 were admitted to level III neonatal intensive care units in Australia and met ANZNN’s high risk criteria, of which 78.0% were preterm.
7.3 /1,000 births fetal death rate (More? Stillbirth and Perinatal Death)
3.2 /1,000 neonatal death rate / live births
10.5 /1,000 perinatal death rate / births
Socioeconomic status of women who gave birth
Women who gave birth in 2005 and were in the least disadvantaged quintile were older and less likely to be Indigenous or smoke during pregnancy, compared with women in the other quintiles.
Proportion of women who had induced or no labour, and the proportion who had an instrumental delivery or caesarean section, increased with socioeconomic advantage.
Proportion of babies with less favourable outcomes, such as preterm birth and low birthweight, decreased with socioeconomic advantage.
(Reference: AIHW National Perinatal Statistics Unit Australia's mothers and babies 2005)
Applied Embryology Links: Normal Development- Statistics | Normal Development- Australian Statistics | World Infant Health Statistics | Abnormal Development - Australian Congenital Malformations Classifications
1995 USA National Survey of Family Growth (NSFG)
Unintended pregnancy is either
(Reference: Pregnancy Risk Assessment Monitoring System USA)
Assisted Reproduction Technology (ART) may include more techniques than, but is sometimes also used to identify, In vitro Fertilization (IVF) (More? In Vitro Fertilization).
Single Embryo Transfers (SET)
Perinatal mortality rate is a measure of perinatal outcomes.
(Reference: AIHW National Perinatal Statistics Unit Assisted Reproduction Technology in Australia and New Zealand 2005)
"The national collation and reporting of birth anomalies data has been suspended in recent years due to concerns about data quality and comparability."
(Reference: modified from AIHW Website)
Ten most frequently reported birth defects in Victoria between 2003-2004 (More? Australian Statistics - Victoria)
Links: Australian Birth Anomalies | Australian Anomalies Classification | Abnormal Development - Australian Statistics - Victoria |
There are many different ways that developmental abnormalities can occur the 2 major types are
Genetic (inherited) and 
Environmental (maternal)
derived abnormalities.
Often not considered, is that pregnancy itself can also expose abnormalities in the mother (congenital heart disease, diabetes, reproductive disorders) that until then had gone undetected.
Teratology Links: Abnormal | Critical Periods of Development
Now consider how different environmental effects during the pregnancy 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. (More? Critical Periods of Development)
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.
Teratology Links: Abnormal Development | Genetic Abnormalities | Maternal Factors | Critical Periods of Development | Abnormal Development - Maternal | Abnormal Development - Fetal Alcohol Syndrome | Abnormal Development - Viral Infection | Rubella Virus | Abnormal Development - Hyperthermia | Abnormal Development - Drugs | Genetic Abnormalities | Abnormal Development - Trisomy 21 (Down Syndrome)
Category A Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester, there is no evidence of a risk in later trimesters, and the possibility of fetal harm appears remote.
Category B Either animal reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women, or animal reproduction studies have shown on adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of risk in later trimesters).
Category C Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women, or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.
Category D There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (eg, if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
Category X Studies in animals or human beings have demonstrated fetal abnormalities or there is evidence of fetal risk based on human experience or both, and the risk of use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.
The following are links to relevant notes pages that cover the key embryology concepts in this tutorial. Links from these pages will provide further detailed information.
Week 2 Abnormalities - Trophoblastic Disease | Placenta
Neural Abnormalities | Abnormal Development - Folic Acid and Neural Tube Defects | Week 3 - Neuralation
Week 1 Blastocyst | BGD - Early Cell Division | Molecular Development
The following are links to relevant notes pages that cover the key teratology concepts in this tutorial. Links from these pages will provide further detailed information.
Abnormal Development | Genetic Abnormalities | Maternal Factors
Critical Periods of Development
Abnormal Development- Australian Statistics | Normal Development- Australian Statistics
Genetic Abnormalities | Abnormal Development - Trisomy 21 (Down Syndrome)
Abnormal Development - Maternal
Abnormal Development - Fetal Alcohol Syndrome
Australian Statistics | Normal Development- Birth - Stillbirth and Perinatal Death | Abnormalities by Systems
Prenatal Diagnosis
Fetal Origins Hypothesis | Intrauterine Growth Retardation
Twinning
Genetic Abnormalities | Down Syndrome | Edwards Syndrome
Maternal Factors
Neural Tube Defects
Fetal Alcohol Syndrome
Smoking
Chemical
Drugs
Radiation
Heavy Metal
Iodine Deficiency
Viral Infection | Rubella | Parvovirus | Databases | NINDS Factsheets
AIHW National Perinatal Statistics Unit Congenital malformations, Australia 1997
Victorian Birth Defects Register (VBDR) | VBDR brochure
Food and Drug Administration (USA) Evaluating the Risks of Drug Exposure in Human PregnanciesCenters for Disease Control and Prevention (CDC, USA) Pregnancy Risk Assessment Monitoring System (PRAMS) collects state-specific, population-based data on maternal attitudes and experiences before, during, and shortly after pregnancy.
Motherisk (Canada) Drugs, chemicals, radiation and herbal products in pregnancy
Office of Children's Health Protection (USA) Critical Periods in Development OCHP Paper Series on Children's Health and the Environment (2003) (PDF document)
International Society for the Study of Trophoblastic Diseases Trophoblastic Diseases
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Welcome to your Tutorial class in Embryology with me in the new medical curriculum!
This class is going to take you through the normal human development features in combination with a description of factors (genetic and environmental) that can impact upon development.
This page is currently being updated for 2008.
Also at the bottom of the same menu is a window to Search UNSW Embryology using any term/concept you do not understand. (note the search window uses Google, so will only work with an active internet connection.
These notes and linked materials have been prepared for Educational purposes only.
Please email Dr Mark Hill if you wish to make a comment about this current project.
