Development From Conception To Birth

1. Development From Conception To Birth • Conception occurs when a sperm and an ovum unite. • A zygote (0-14 days) is produced by union of a sperm and an egg.

2. Development From Conception To Birth • The child inherits half of its genetic makeup from each parent through meiosis of 46 chromosomes, 23 from each parent.

4. Development From Conception To Birth • Implantation -zygote embeds itself in wall of uterus and develops into an embryo (2-9 weeks) • 9-40 weeks = fetus.

5. Differentiation development of cells into tissues and organs. • controlled by cell's expression of genes with environment.

6. Sexual differentiation • From fertilization - six weeks of development, male and female embryos have undifferentiated gonads (sex glands: ovaries or testes).

7. Sexual differentiation • a gene on the Y chromosome directs the undifferentiated gonads to become testes. • If Y chromosome is not present (as in normal females), undifferentiated gonads will become ovaries (female epigenesist)

8. Fetal period • Gestation = pregnancy • Full term = 40 weeks • Viability = ability to survive outside womb • Premature birth = prior to 37 weeks or birth weight of less than 5.5 pounds

10. Development From Conception To Birth • Despite protection of mother's body, baby's development may be influenced by mother's diet, physical condition, drugs she may use, including tobacco and alcohol.

12. Prenatal Development • Folic acid (vitamin B9 or folate) important in preventing neural tube defects such as spina bifida • crucial in development of DNA. • plays large role in cell growth and development and tissue formation

13. Prenatal Development • 400 micrograms (0.4 milligrams) daily of folic acid • Mom needs 350 extra calories daily • Maintain normal exercise (unless complications arise)

14. Alphafetoprotein • AFP is a protein secreted by the fetal liver and excreted in the mother's blood.

15. Elevated AFP in mother’s blood can indicate neural tube defect in baby such as spina bifida. Lower levels of AFP suggest possible Down’s syndrome or other chromosomal defect.

16. Ultrasound

17. Ultrasound/ sonogram

18. Amniocentesis

19. CV Sampling • Chorionic villi are tiny parts of placenta formed from the fertilized egg, having same genes as the fetus. • CVS can identify chromosomal problems: Down syndrome, cystic fibrosis, Tay-Sachs disease and sickle cell disease

20. Teratogens • Agents capable of causing developmental abnormalities in utero. • effect related to type of agent, dose and duration and time of exposure

22. Environmental Insults • 1. Malnourishment • Malnourished mother = malnourished baby • Miscarriages and stillbirths

23. Teratogenic drugs • Anti-nausea - thalidomide • Prevent miscarriages: Synthetic hormones - diethylstilbestrol (DES)—cancer in children • Alcohol – FAS • Tetracycline- bone development

25. Environmental Insults • 2. Alcohol • Migrating cells go • TOO FAR • F.A.S.

26. Environmental Insults • 3. Radiation • Cells don’t go far enough • After 8 weeks/ problems • Mental retardation • Growth retardation

27. Environmental Insults • 4. Smoking cigarettes • Poisons and lack of oxygen • Fetus curls up/ trauma • Low birth weight/stillbirth • Fetal Tobacco Syndrome

28. Teratogens • Cocaine, marijuana – reflexes, attention, mood (short-term?) • Rubella – heart/brain defects, deafness and cataracts/blindness • Stress – LBW, premature, miscarriage • HB Pressure – LBW/ constricted blood flow to placenta

30. Development In Infancy • Newborn infants are able to recognize voices (audition) and faces (vision), to make appropriate facial reactions to taste and smell, and even to learn.