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Prenatal Development and Birth

Prenatal Development and Birth. Chapter 4. The Period of the Zygote Zygote  blastocyst Cell differentiation % of blastocysts that fail to implant?. Periods of Prenatal Development. Periods of Prenatal Development. The Period of the Zygote (con’t)

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Prenatal Development and Birth

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  1. Prenatal Development and Birth Chapter 4

  2. The Period of the Zygote Zygote  blastocyst Cell differentiation % of blastocysts that fail to implant? Periods of Prenatal Development

  3. Periods of Prenatal Development • The Period of the Zygote (con’t) • Outer layer of blastocyst develops into: • Amnion • Chorion • Placenta • Umbilical cord **note that these structures actually develop during the period of the embryo

  4. Periods of Prenatal Development • The Period of the Embryo • From implantation (week 3) to week 8 • Embryonic disk is already differentiating into: • Ectoderm (nervous system, skin, hair, sensory receptors • Mesoderm (muscles, bones, circulatory system, reproductive system, excretory system) • Endoderm (digestive system, lungs, urinary tract, other internal organs)

  5. Periods of Prenatal Development • The Period of the Embryo (con’t) • By 4th week, heart has formed and begun to beat • Becomes more human in appearance during 2nd month • Sexual differentiation during 7th – 8th weeks

  6. Periods of Prenatal Development • The Period of the Fetus • Final 7 months of pregnancy • Fetus • Digestive and excretory systems functional • Sex detected by ultrasound by end of 3rd month • Kicks and movements strong enough to be felt • Organ systems mature rapidly during final 3 months

  7. Periods of Prenatal Development • The Period of the Fetus (con’t) • Viable between 22-28 weeks • Receives antibodies • Assume upside-down position in final weeks • Weight of head • Shape of uterus

  8. Trends in Development • Cephalocaudal Trend • Proximodistal Trend

  9. Teratogens • Root word means “formation of monsters” • Harm isn’t always simple or straightforward • Amount and length of exposure • Genetic makeup of mother/baby • Presence of several negative factors

  10. Teratogens • Same defect  different teratogens • One teratogen  different defects • Some effects seen later

  11. Teratogens • Age of baby • Sensitive period

  12. Teratogens • Paternal influences often overlooked • Direct and indirect effects • Second hand smoke • Chemicals • Cocaine can “hitchhike” • Smoking, alcohol, drug use  sperm • Diets low in vitamin C

  13. Other Factors • Exercise • Nutrition • Emotional stress • Rh blood incompatibility • Maternal/Paternal age • Older  less fertile, more risk of disorders • Younger  increased risk of prematurity, infant death

  14. Other Factors • Infectious Diseases • Prenatal Care • Previous births

  15. Perinatal Environment • Environment surrounding birth • Stages of childbirth • Contractions • Delivery • Afterbirth • Newborn appearance

  16. Perinatal Environment • Assessing the Newborn • Apgar scale • 1 minute and 5 minutes after birth

  17. Perinatal Environment • Assessing the Newborn • Neonatal Behavioral Assessment Scale (NBAS) • Several days after birth • 20 inborn reflexes • Reactions to comforting and social stimuli • Unresponsiveness may indicate neurological problems • Can be a parent teaching tool

  18. Perinatal Environment • Complications • Anoxia • Severe  cerebral palsy, mental retardation • Mild  irritability, motor/cognitive delays • Chances have been reduced with fetal monitoring • Respiratory distress syndrome • Complicated delivery • Forceps • Cesarean • Medications

  19. Preterm and Small-for-Date • Preterm = born more than 3 weeks early, but appropriate weight for time in womb • Small-for-Date = underweight due to slow fetal growth • Greater risk than preterm • Causes include smoking, drug use, stress, lack of prenatal care, multiple births, social support • Postterm = born after 42 weeks

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