1. Chapter 4 Prenatal Development and Birth

2. Chapter 4- Prenatal Development Time of fastest development Conception –Ova (eggs) travels from ovary to uterus –Penetration by 1 of 300-500 sperm –ZYGOTE (fertilized egg)

3. Prenatal Development and the Zygote

4. Menu LO 7.6 Germinal, embryonic, and fetal periods of pregnancy

5. Prenatal Stages Germinal period: days 1-14 (0 - 2 weeks) –Zygote’s implantation into uterine wall: 1/2 are successful –Zygote divides many times through mitosis to form blastocyst (about 150 cells) –Miscarriage: 8-30% (recognized) to 33% (unrecognized) Embryonic period: 3 rd to 8 th week (3 rd week - 2 nd month) –Organogenesis – every major organ takes shape –Sexual differentiation – begins during 7 th & 8 th week

6. Outer Layer of Blastocyst (150 cells) forms: Amnion – a watertight membrane that fills with fluid that protects the embryo Placenta – provides nourishment by mother’s blood vessels Umbilical cord – connection between embryo and mother Placental barrier – protects developing child from many harmful substances, and allows small molecules exchanged

8. Inner cell mass of blastocyst forms : Ectoderm – (brain and spinal cord) Mesoderm – muscle tissue, cartilage, bone, heart, arteries, kidneys, and gonads Endoderm – gastrointestinal tract, lungs, and bladder Neural plate forms neural tube (bottom is spinal cord) Top of tube forms into forebrain, midbrain, hindbrain

9. Figure 4.3

10. Fetal period: 9 th week – birth –Proliferation of neurons (250,000 per minute) – Migration of neurons –Differentiation of stem cells Age of viability – around 23-25 weeks (fetus has possibility of surviving outside uterus) 3 rd Trimester – myelination

12. Prenatal Development and the Newborn 40 days 45 days 2 months 4 months

13. Prenatal Environment Teratogen: harmful environmental agent –Harms the developing fetus –Critical Period: Organogenesis –Dosage & duration –Genetic make-up: susceptibility

14. Menu LO 7.6 Germinal, embryonic, and fetal periods of pregnancy

15. Teratogens Thalidomide (for morning sickness) All or parts of limbs missing

16. Sudden Infant Death Syndrome

17. Fetal Alcohol Syndrome

18. “Copyright© Allyn & Bacon 2006” Low birth weight Developmental delay Epilepsy Poor coordination / fine motor skills Behavioral problems

19. 2 six week old infants FAS Normal child

20. Teratogens - Diseases Rubella (German Measles) –Blind, deaf, heart, brain Syphilis:miscarriage, blind, deaf, heart, brain –After 18 th week AIDS mothers transmit to babies (15%-35%) –Prenatally, perinatally, postnatally

21. Teratogens – Environmental Hazards Radiation: MR, leukemia, cancer, mutations, spontaneous abortions, etc. –Avoid X-rays when pregnant Pollutants –In air and water – Lead - MR (also postnatally) Anoxia – Oxygen shortage –can cause mental retardation or cerebral palsy

24. Postnatal Depression Baby Blues, mild, common Postpartum depression: 1/10 –Previous depression common Children of depressed mothers –Insecurely attached, less responsive –Negative to other children

25. APGAR TEST Provides a quick assessment of the newborn’s: 1) Heart rate (0-2 points) 2) Respiratory effort (0-2 points) 3) Muscle tone (0-2 points) 4) Color (0-2 points) 5) Reflex irritability (0-2 points) The Apgar test is given immediately and 5 minutes after birth 7 or higher = good shape 4 or lower = at risk

26. The Neonatal Environment Culture, early socialization, health status –E.g., low birth-weight babies (8% in US) Less than 5 1/2 lbs or 2500 grams Strongly linked to low SES Environment: neonatal intensive care Risk: blindness, deafness, CP, autism, cognitive, and later academic problems