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Prenatal Development

Prenatal Development. Haffner, W. J. J.(2007). Development before birth. In Batshaw, M. L., Pelligrino, L. & Roizen N. J. (Eds.). Children with disabilities (6 th ed.). (pp. 23-34). Baltimore, MD: Paul H. Brookes Publishing Company.

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Prenatal Development

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  1. Prenatal Development Haffner, W. J. J.(2007). Development before birth. In Batshaw, M. L., Pelligrino, L. & Roizen N. J. (Eds.). Children with disabilities (6th ed.). (pp. 23-34). Baltimore, MD: Paul H. Brookes Publishing Company. Moore, K. L., & Persaud, T. V. N. (1993). The developing human: Clinically oriented embryology (5th ed.). Philadelphia, PA: W. B. Saunders Company. Revised June 2008 Development of Young Children with Disabilities#872.514 (61)Carol Ann Heath

  2. Pregnancy • Dating the pregnancy • EGA- estimated gestational age (14 days longer than conceptional age, includes time between LMP and ovulation) • LMP- menstrual age is the time from the first day of the last menstrual period

  3. Fertilization • If sexual intercourse occurs near the time of ovulation when the mature ovum (egg) is released, conception can occur.

  4. Average duration of pregnancy is 280 days, or 40 weeks • EDD (estimated due date) = EDC (estimated date of confinement) • EDD- add 7 days to first day of LMP (last menstrual period) and subtract 3 months

  5. Preterm delivery- prior to 38 complete weeks EGA (estimated gestational age) • Full term- between 38 and 42 weeks EGA • Post term birth- EGA greater than 42 weeks

  6. Birth • A child is born • Preceding months are complex and numerous steps • The egg is fertilized and implants • In-utero development occurs rapidly

  7. When does the greatest risk for severe developmental disabilities occur? • The greatest risk for severe developmental disabilities occurs in the period between conception/implantation and birth (Decoufle et al., 2001) • Fewer than 10% of developmental disabilities occur during labor and delivery (Batshaw, 2002)

  8. Fertilization • When the mature ovum (egg) is released and is penetrated by a sperm (the sperm can remain viable in the tubes for 2-3 days; the egg can only be fertilized for 12-24 hrs)

  9. The Cell • Bodies are composed of over 100 trillion cells • Many types of cells • Each cell divided into two compartments: (1) central- the nucleus (2) outer area- the cytoplasm

  10. The Nucleus • Houses chromosomes (Greek for “colorful bodies”) • Contain the genetic code- DNA • DNA (1) deoxyribonucleic acid (2) contains physical and biochemical properties

  11. Chromosomes • Humans- 46 chromosomes • 46 (diploid number) are divided into 23 (haploid number) pairs of complementary chromosomes • In every chromosome pair, one comes from the mother/one comes from the father

  12. Conception: • Egg & sperm cells each contain only 23 chromosomes • Sperm contributes 23 + X or 23 + Y • Ovum contributes 23 + X • Germs cells fuse to produce fertilized egg = • XX (female) • XY (Y contributes “maleness”)

  13. Embryonic Development: • Day 1: Fertilization [2 weeks after LMP] • Sperm + Ovum = ZYGOTE • Day 2: Zygote divides; the group of multiplying cells is called the morula

  14. Day 4 & 5: Blastocyst forms (develops hollow cavity) The blastocyst lies free in the uterine cavity for about 2 days before attaching, or implanting, to the endometrium (inside wall of the uterus) • This marks the formal beginning of pregnancy, nearly 5-7 days after ovulation & fertilization

  15. What three types of cells does the embryonic stem differentiate into? • The embryonic stem cells differentiate into three types of cells: • Ectoderm • Mesoderm • Endoderm

  16. Embryonic development is divided into what two stages? • Embryonic- lasts from week 3 to week 8 after ovulation and fertilization, or week 5 to week 10 after the first day of the last menstrual period • Fetal- begins 8 weeks after ovulation and fertilization

  17. Embryonic Development [Cont.]: • Day 6: Early implantation • Day 7: Full attachment of embryo in uterus • In general, substances taken in wks 1 & 2 will either kill the embryo or enough cells recover to allow normal development • In general, no teratogenic effects

  18. Embryonic Development [Cont.]: • Day 15: 1st missed period • Day 16: 1st indications of neural groove • Week 3: Placenta formed; • Week 4: Primitive; neural tube forms • Ear & eyes, lips, palate, jaw • Upper limb buds

  19. Embryonic Development [Cont.]: • Week 5: • Heart tube forms • Lower limb buds • Week 6: • Oral + nasal cavities migrate • If abnormal = Cleft lip/palate • Tail present

  20. Embryonic Development [Cont.]: • Week 7: • Limbs bend • Fingers/toes webbed • Week 8: • Tail stub present

  21. Embryonic Development [Cont.]: • Week 8: Fetus • Head rounder • Tail gone • Cannot distinguish gender • Week 9: End of embryonic period • CR = 3.25 inches • Start of fetal development

  22. Fetal Development: • Essential structures present • 10th week: • Face appears child like • Genitalia distinguishable • Tremendous neurologic growth • Organ maturation

  23. Fetal Development [Cont.]: • 5th & 6th mo- fingernails form, skin thickens, movements purposeful; • End of 6th mo- weighs 2 lbs, 14 inches long • Gestation = 38 weeks (since conception) • Prematurity = < 35 weeks (3 weeks early) • Postmaturity = > 40 weeks (2 weeks late)

  24. Having a Baby • Approximately 266 days after conception, the process of labor begins. • The mothers immune system shuts down during the previous nine months but then decides to reject the baby.

  25. Labor • First stage- Mild contractions with may be confused with Braxton-Hicks which occur throughout the pregnancy; • Within hours the contractions become stronger, longer and more frequent, allowing the babies head to get into position for delivery- the vertex position;

  26. Labor- • the presence of regular uterine contractions leading to progressive effacement (thinning) • Dilation of the cervix • Expulsion of the fetus

  27. First Stage • Uterine contractions bring about effacement and progressive dilation of the cervix

  28. Second stage • Baby’s head pushes through the birth canal and appears at the vaginal opening; • Cervix becomes fully dilated;

  29. Third Stage • Usually lasts 10 to 15 minutes • The complete expulsion of birth of the newborn • Nose and mouth are bulb-suctioned to clear airway

  30. Umbilical cord is wrapped around the neck in ¼ of births (nuchal cord) • Cord is clamped and cut

  31. Other issues • Cesarean delivery- baby delivered through an incision in the abdomen and uterus; 5% in 1965 to 27.6% in 2003 (highest rate). • Dystocia- difficult labor • Protraction disorders • Cessation

  32. In 9 out of 10 cases, the result is a ruddy-cheeked, screaming, healthy baby.

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