2. 1 Development Patterns Cephalocaudal Proximal-distal

3. 2 Embryonic Development ZygoteConception-2 weeks: Zygote –about half survive this stage –rapid cell differentiation –~ 10 days outer part of zygote attaches to uterine wall; placenta develops

4. 3 Embryonic Development First month (0- 4 weeks after conception) –Wt. is 400mg, Ht. is 1 cm. –Limb buds are present –Organs start to form –Heart pumps blood –C-shaped body. –Head is 1/3 of entire body.

5. 4 Second month (5- 8 weeks) –Formation of head and facial features. –Skeleton is visible. –Organogenesis is complete. –Eyes formed and open –Extremities have developed (some movements). –Wt 1 gm, Ht is 2.5cm.

6. 5 Third month (9- 12 weeks) –Teeth begin to appear. –Kidneys begin to function –Some respiratory-like movements. –Begin to swallow amniotic fluid. –Grasp, sucking, blinking and withdrawal reflexes present. –Gender easily distinguished –Weight 30 gm. –Sleeping and activity patterns are distinguishable

7. 6 Fourth month (13- 16 weeks) –Much spontaneous movements. –Moro reflex present. –Rapid skeletal development. –Meconium present. –Downy hair (lanugo) appears on body. –Weight 120 gm.

8. 7 Fifth month (17- 20 weeks) Mother usually feels movement (quickening) Vernix caseosa appears. Eyebrows and hair appear. Strong grasp reflex present. Permanent teeth buds appear. Brown fat is formed. Heart sound can be heard with stethoscope. Weight 360gm.

9. 8

10. 9 Sixth month (21- 24 weeks) –Extra uterine life possible. –Begin to produce surfactant. –Skin has red wrinkled appearance. –Alternative periods of sleep and activity. –May respond to external sounds. –May try to find comfortable position. –Weight 720 gm.

11. 10 Seventh month (25- 28 weeks): –Respiratory and central nervous system sufficiently developed. –Eye lids open and close spontaneously. –Assumes head- down position in uterus. –Weight 1200 gm.

12. 11 Eighth month (29- 32 weeks): –Begins to store fat and minerals. –Testes descend into scrotal sac. –Lanugo begins to disappear from face. –Skin begins to lose reddish color. –Weight 2000 gm.

13. 12 Ninth month (33- 36 weeks): –Increased iron storage by liver. –Increased development of lungs. –May become more or less active due to space tightness. –Weight 2800 gm.

14. 13 Tenth month (37- 40 weeks): –High absorption of maternal hormones. –Continued storage of fat and minerals. –Ready for birth. –Weight 3200 gm.

15. 14 Chromosomal factors Developmental factors –Teratogens –Drugs –Maternal Nutrition –Maternal disease –Stress –Fetal factors Factors that affect development

16. 15 Teratology Teratogens –Any agent that causes a birth defect –After Greek “monster creating” Variables affecting influence of teratogens –Timing of exposure –Intensity & duration of exposure –Number of harmful influences present –Biogenetic vulnerability of mother & infant sensitivity

17. 16 Most serious damage from teratogens in first 2-8 wks Zygote Embryonic period (wks) Fetal Period (wks) Period of susceptibility to functional defects Period of susceptibility to structural defects Fig. 4.4 123456789163238 Teratogens and Timing of Their Effects on Prenatal Development Central nervous system Heart Arms Eyes Legs Ears Teeth Palate External genitalia

18. 17 TeratogensTeratogens: –Viruses: Rubella - most serious if exposed between 4-8 weeks; later prenatal exposure seldom life-threatening (congenital deafness common) HIV- 20-50% may pass on virus prenatally or during delivery

19. 18 Prescription Drugs Thalidomide – sedative used in early 1960s –Infants with severe defects Diethylstibestrol (DES) – used to prevent miscarriages (cancer of reproductive system) –Abnormalities appeared in adulthood Antibiotics (streptomycin, tetracycline) Some depressants Certain hormones (progestin, synthetic estrogen) Accutane( used to treat acne) Coffee

20. 19 Illegal Drugs Cocaine - reduced birth weight, length, and head circumference; impaired motor development; poor attentional skills Marijuana - increased tremors and startles among newborns; poorer verbal and memory development Heroin – addiction & withdrawal symptoms including tremors, irritability, abnormal crying, disturbed sleep, impaired motor control; attention deficits

21. 20 Environmental Hazards Radiation: nuclear environments, X-rays, computer monitors Chemicals: carbon monoxide, mercury, lead, pesticides. Heat: saunas, hot tubs

22. 21 Fetal alcohol effects (FAE); more severe form (FAS) Fetal Alcohol Syndrome (FAS) –Low birth weight; lack of responsiveness –Facial deformities; defective limbs, face, and heart –Below average intelligence, with some cases of mental retardation –Adults with FAS found to have a high incidence of mental disorders, such as depression or anxiety Alcohol and Pregnancy

23. 22 Higher fetal and neonatal deaths Higher incidence of preterm births and lower birth weights Related to poorer language development & cognitive development by age 4 Respiratory problems and SIDS are more common Nicotine

24. 23 Diet Pills Aspirin ( baby Aspirin is prescribed for problem in the placenta) Caffeine –Small increase in the risks for spontaneous abortion and low birth weight occurs for pregnant women consuming >150 mg caffeine per day. Nonprescription Drugs

25. 24 Maternal Age Adolescence Older mothers

26. 25 Domestic Violence 7-8% pregnant women are beaten Twice the miscarriage rates

27. 26 Important factors of nutritional status are –total number of calories –levels of protein, vitamins, and minerals –folic acid - linked with neural tube defects, such as spina bifida Poor diet linked to infant mortality & prematurity Malnourished infants have significantly reduced number of brain cells Nutrition

28. 27 Severe or prolonged stress increases medical complications & infant abnormalities Linked to spontaneous abortion, difficult labor, premature birth, low birth weight, newborn respiratory difficulties Effects of Stress on Pregnancy

29. 28 Exposure to lead, radiation, certain pesticides, and petrochemicals may cause abnormalities in sperm that lead to miscarriage or disease. Diet low in vitamin C, increases risk of birth defects and cancer. Connection between cocaine use in fathers and birth defects. Fathers’ smoking during pregnancy may lead to lower birth weight and potential for their offspring developing cancer. Older fathers have higher risk for birth defects (e.g., Down syndrome & dwarfism. Paternal Factors