Revision as of 11:56, 16 October 2009

Birth and Postnatal Development

Introduction

Historic model of birth

There are a great number of comprehensive, scientific and general, books and articles that cover Parturition, Birth or Childbirth.

Birth or parturition is a critical stage in development, representing in mammals a transition from direct maternal support of fetal development, physical expulsion and establishment of the newborns own respiratory, circulatory and digestive systems.

Textbooks

Human Embryology (2nd ed.) Larson Chapter 15 p471-488

The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Chapter 7 p129-167

Gestation Period

Newborn

The median duration of gestation for first births from assumed ovulation to delivery was 274 days (just over 39 weeks). For multiple births, the median duration of pregnancy was 269 days (38.4 weeks).

"...one should count back 3 months from the first day of the last menses, then add 15 days for primiparas or 10 days for multiparas, instead of using the common algorithm for Naegele's rule." Reference: Mittendorf R, Williams MA, Berkey CS, Cotter PF. The length of uncomplicated human gestation. Obstet Gynecol. 1990 Jun;75(6):929-32

Historically, Franz Carl Naegele (1777-1851) developed the first scientific rule for estimating length of a pregnany.

Preterm Birth

A study has shown that risks of preterm birth in low abnormal birth weight (intrauterine growth restriction) and high (large for gestational age) categories are 2- to 3-fold greater than the risk among appropriate-for-gestational-age infants.

In another study of placenta previa, low birth weight is due mainly to preterm delivery and to a lesser extent with fetal growth restriction.

Reference: Lackman F, Capewell V, Richardson B, daSilva O, Gagnon R. The risks of spontaneous preterm delivery and perinatal mortality in relation to size at birth according to fetal versus neonatal growth standards. Am J Obstet Gynecol. 2001 Apr;184(5):946-53.

Ananth CV, Demissie K, Smulian JC, Vintzileos AM. Relationship among placenta previa, fetal growth restriction, and preterm delivery: a population-based study. Obstet Gynecol. 2001 Aug;98(2):299-306.

Respiration

Lungs at birth collapsed and fluid-filled - replaced with air by powerful inspiratory movement and absorption through the alveoli
Respiratory Rate is higher than adult (30 breaths/minute).
Rib Orientation - Infant rib is virtually horizontal, allowing diaphragmatic breathing only. Adult rib orientation is oblique (both anterior and lateral views), allows for pump-handle and bucket handle types of inspiration.

Neonatal Testing

APGAR

Measured at one and five minutes after birth the Score values are totalled for all indicators: 7-10 is considered normal, 4-7 may require resuscitative measures, 3 and below require immediate resuscitation.

In recent years there has been some controversy of the relevance and accuracy of some of the criteria used in this test, though many feel it is still an invaluable initial assessment tool particularly where medical services are limited.

Indicator	Score 0	Score 1	Score 2
Activity (muscle tone)	Limp; no movement	Some flexion of arms and legs	Active motion
Pulse (heart rate)	No heart rate	Fewer than 100 beats per minute	At least 100 beats per minute
Grimace (reflex response)	No response to airways being suctioned	Grimace during suctioning	Grimace and pull away, cough, or sneeze during suctioning
Appearance (color)	The baby's whole body is completely bluish-gray or pale	Good color in body with bluish hands or feet	Good color all over
Respiration (breathing)	Not breathing	Weak cry; may sound like whimpering, slow or irregular breathing	Good, strong cry; normal rate and effort of breathing

Reference: Apgar, V. A proposal for a new method of evaluation of the newborn infant. Curr Res Anesth Analg. 1953 Jul-Aug;32(4):260-7. PMID:13083014

Guthrie Test

Robert Guthrie

Guthrie card

Blood is collected using a heelprick and spotted onto a test sheet to dry for later testing.
Different countries and medical services have different policies on not only what will be diagnostically tested, but also how long the test card will be kept following analysis.

Routine Screened Disorders

Biotinidase Deficiency (OMIM)
Congenital Adrenal Hyperplasia (CAH) (OMIM)
Congenital Hypothyroidism (CH)
Congenital Toxoplasmosis
Cystic Fibrosis (CF) (OMIM)
Galactosemia (GAL) (OMIM)
Homocystinuria (OMIM)
Maple Syrup Urine Disease (MSUD) (OMIM)
Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCAD) (OMIM)

Heart

An electrocardiogram (ECG / EKG) is an electrical recording of the heart which may identify electrical disorders including long QT syndrome.

Hip Displasia

Non-specific hip instability is a common finding in newborns, particularly in females.
More than 80% of clinically unstable hips at birth resolve spontaneously. Screening newborns for Developmental dysplasia of the hip (DDH) shows an incidence in infants between 1.5 and 20 per 1000 births. This incidence is influenced by several factors (diagnostic criteria, gender, genetic and racial factors, and age of the population).

Links: Musculoskeletal Abnormalities- Congenital Dislocation of the Hip | [hipdyssyn.pdf Screening for Developmental Dysplasia of the Hip PDF] | Screening for developmental dysplasia of the hip. Evidence synthesis no. 42. Rockville, Md.: Agency for Healthcare Research and Quality http://www.ahrq.gov/downloads/pub/prevent/pdfser/hipdyssyn.pdf | U.S. Preventive Service Task Force. Screening for developmental dysplasia of the hip: recommendation statement. Am Fam Physician. 2006 Jun 1;73(11):1992-6.

Hearing

The incidence of significant permanent hearing loss is approximately 1-3/1000 newborns.
Neonatal hearing screening is carried out in the USA, UK and in Australia (2002 NSW Statewide Infant Screening Hearing Program, SWISH) There is a general guide giving a timetable for a number of simple responses that a neonate should make if hearing has developed normally.
State Wide Infant Screening Hearing Program (SWISH) a newborn hearing testing program using an automated auditory response technology (AABR). Program was introduced in NSW Australia in 2002 across 17 area health service coordinators. It is thought that in NSW 86,000 births/year = 86-172 babies potentially born with significant permanent hearing loss.
Automated Auditory Brainstem Response (AABR) uses a stimulus which is delivered through earphones and detected by scalp electrodes. The test takes between 8 to 20 minutes and has a sensitivity 96-99%.

Abnormalities

Labor Abnormalities

Premature Labor - occurs 7 -10% in humans, contributes 75% perinatal mortalities

Underdeveloped Systems - particularly respiratory, surfactant, hyaline membrane disease (see respiratory development lecture)

Placental Abnormalities

placenta accreta - abnormal adherence, with absence of decidua basalis
placenta percreta - villi penetrate myometrium
placenta previa - placenta overlies internal os of uterus, abnormal bleeding, cesarian delivery

Breech Delivery

Historically, breech-born children were called agrippi, meaning "delivered with difficulty" (aegre parti).
Breech position - occurs in about 3% of fetuses when buttocks or lower limb are presented to the birth canal rather than normal cephalic (head-first) position (presentation).
Associated increased - perinatal mortality, perinatal morbidity, recurrence in successive siblings

Current research suggests that genetically that both men and women delivered in breech presentation at term could also contribute to an increased risk of breech delivery in their offspring. ([#18369204 Nordtveit TI, etal., 2008])

Links

UNSW Embryology Introduction | Birth Overview | Abnormalities | Caesarean | Apgar | Premature | Low Birth Weight | Placental Cord Clamping | Cardiovascular | Stillbirth and Perinatal Death | Molecular Web Links
Birth Statistics Australian Birth Statistics | International and Australian Population Statistics | WHO Normal Population Statistics | WHO Fact Sheets | Global Perinatal and Maternal Causes of Death | Population Comparisons between Countries | Developed and developing | Australian neighbours | Australian Trading Partners

Birth Terms

amniotomy - birth medical procedure thought to speed labor, where the amniotic sac is artificially ruptured using a tool (amniohook).

breech - fetal buttocks presented first and can also occur in different forms depending on presentation (complete breech, frank breech, footing breech, knee breech).

decidual activation - increased uterine proteolysis and extracellular matrix degradation.

dilatation - opening of the cervix in preparation for birth (expressed in centimetres).

effacement - shortening or thinning of the cervix, in preparation for birth.

forceps - mechanical "plier-like" tool used on fetal head to aid birth.

fetal macrosomia - clinical description for a fetus that is too large, condition increases steadily with advancing gestational age and defined by a variety of birthweights. In pregnant women anywhere between 2 - 15% have birth weights of greater than 4000 grams (4 Kg, 8 lb 13 oz).

membrane rupture - breaking of the amniotic membrane and release of amniotic fluid (water breaking).

morbidity - (Latin, morbidus = "sick" or "unhealthy") refers to a diseased state, disability, or poor health due to any cause.

presentation - how the fetus is situated in the uterus.

presenting part - part of fetus body that is closest to the cervix.

second stage of labour - passage of the baby through the birth canal into the outside world.

Vacuum Extractor - suction cap device used on fetal head to aid birth.

Vertex Presentation (cephalic presentation) where the fetus head is the presenting part, most common and safest birth position.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Course Content 2009

Cite this page: Hill, M.A. (2024, April 24) Embryology 2009 Lecture 23. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2009_Lecture_23

What Links Here?

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 ==Links==
 * '''UNSW Embryology''' [http://embryology.med.unsw.edu.au/Child/birth1.htm Introduction] | [http://embryology.med.unsw.edu.au/Child/birth3.htm Birth Overview] | [http://embryology.med.unsw.edu.au/Child/birth2.htm Abnormalities] | [http://embryology.med.unsw.edu.au/Child/birth6.htm Caesarean] | [http://embryology.med.unsw.edu.au/Child/apgar.htm Apgar] | [http://embryology.med.unsw.edu.au/Child/birthpremature.htm Premature] | [http://embryology.med.unsw.edu.au/Child/birthweight.htm Low Birth Weight] | [http://embryology.med.unsw.edu.au/Child/birth8.htm Placental Cord Clamping] | [http://embryology.med.unsw.edu.au/Child/birthheart.htm Cardiovascular] | [http://embryology.med.unsw.edu.au/Child/birth7.htm Stillbirth and Perinatal Death] | [http://embryology.med.unsw.edu.au/Child/birth10.htm Molecular] [http://embryology.med.unsw.edu.au/Child/birthlink.htm Web Links]
+* '''Birth Statistics'''  [http://embryology.med.unsw.edu.au/Stats/page2.htm Australian Birth Statistics] | [http://embryology.med.unsw.edu.au/Stats/page1.htm International and Australian Population Statistics] | [http://embryology.med.unsw.edu.au/Stats/page3.htm WHO Normal Population Statistics] | [http://www.who.int/inf-fs/en/index_n.html WHO Fact Sheets] | [http://embryology.med.unsw.edu.au/Stats/page3a.htm#perinatal Global Perinatal and Maternal Causes of Death] | [http://embryology.med.unsw.edu.au/Stats/page4a.htm Population Comparisons between Countries] | [http://embryology.med.unsw.edu.au/Stats/page4a.htm#Population%20Data Developed and developing] | [http://embryology.med.unsw.edu.au/Stats/page4a.htm#au1 Australian neighbours] | [http://embryology.med.unsw.edu.au/Stats/page4a.htm#au2 Australian Trading Partners]
 == Birth Terms ==

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