Slide 1

2009 The McGraw-Hill Companies, Inc. All Rights Reserved Prenatal Development and Birth Chapter Three Slide 2 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Stages of Prenatal Development Encompasses 38 weeks or 9 months Contains 3 periods (trimesters) Zygote first 2 weeks of life Embryo 3rd wk of gestation to 8th wk of life Amniotic sac and fluid protective buffer Placenta joins infant by umbilical cord Umbilical cord tube of blood vessels Fetus 9th week until birth Slide 3 2009 The McGraw-Hill Companies, Inc. All Rights Reserved The three trimesters of prenatal development 16 weeks 20 weeks 24 weeks Less than 1/10th of an inch long 8 weeks Less than 1 inch long 32 weeks About 16.5-18 inches long, weighs 4 to 5 pounds 36 to 38 weeks 19 inches long, weighs 6 pounds About 5.5 inches long, weighs about 4 ounces About 10-12 inches long, weighs 1/2 to 1 pound About 11-14 inches long, weighs 1 to 1.5 pounds 28 weeks About 14-17 inches long, weighs 2.5 to 3 pounds 12 weeks About 3 inches long, weighs about 1 ounce Conception to 4 wks 16 weeks 20 weeks 24 weeks First trimester begins Third trimester begins Second trimester begins Slide 4 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Umbilical cord Umbilical arteries Umbilical vein Uterus Maternal portion of placenta Placenta Fetal portion of placenta The Placenta and the Umbilical Cord Slide 5 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Stages of Prenatal Development Some destructive substances such as drugs, viruses, and antibodies can pass through placenta In the embryonic period Ectoderm forms outer skin, nails, hair, and nervous system Mesoderm forms muscles and skeleton Endoderm forms vital organs and glands Slide 6 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Stages of Prenatal Development Neural folds begin to close to form CNS, failure to close results in spina bifida Cephalocaudal development pattern of human physical growth proceeds from head downward Proximal-distal development human growth occurs first in central areas and then extends outward Slide 7 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Cephalocaudal development Slide 8 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Stages of Prenatal Development Most miscarriages occur during the embryonic period During fetal period Rapid muscular development occurs Rapid development in CNS Fetal movement usually by 4th month Reflexes usually appear about 5 months After 5 months, lanugo (soft hair) develops Eyes can open and close by 6th month Slide 9 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Stages of Prenatal Development Premature birth occurring before fetus is 6 months old results in inadequate surfactant (liquid in lungs that sends oxygen into bloodstream) may cause respiratory distress syndrome Age of viability 22 to 26 weeks Slide 10 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Prenatal exposure to teratogens may cause developmental deviations Teratogens Exert effects largely during critical periods Each has own effects Maternal/fetal genotypes may counteract Ones effects can intensify effects of others Some may have no effect on mothers The longer the exposure, the worse it is Slide 11 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Most serious damage from teratogens in first 2-8 wks Zygote Embryonic period (wks) Fetal Period (wks) 123456789163238 Teratogens and Timing of Their Effects on Prenatal Development Period of susceptibility to functional defects Period of susceptibility to structural defects Heart Arms Eyes Legs Ears Teeth Palate External genitalia Central nervous system Slide 12 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Premature birth, low birthweight, or other physical problems can affect emotional bond of parent and child Environmental dangers include legal and illegal drugs Slide 13 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Legal and illegal drugs Nicotine and alcohol Sudden death syndrome Fetal alcohol syndrome Other developmental effects lower IQ scores, poor school performance, higher risk for dependency problems later in life Slide 14 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Legal and illegal drugs Heroine, cocaine, and other drugs Withdrawal symptoms in newborns Birth defects Prenatal effects of drugs are of concern Newborns symptoms related to extent of mothers addiction Addicted infants behaviors affect parent-child interactions Slide 15 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Environmental toxins Radiation, lead, mercury, herbicides, pesticides, household cleaners, food additives, cosmetics Exposure to vehicle exhaust fumes, PCBs, contaminated industrial waste, electrical transformers can be harmful Avoid x-rays Males exposed to environmental toxins or drink can cause birth defects in offspring Slide 16 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Medical interventions Therapeutic disasters Diethylstilbestrol (DES): synthetic hormone Thalidomide for morning sickness Phocomelia missing limbs, facial deformities, flipper babies Other drugs (prescriptions) Tranquilizers Anticonvulsants Risks in the Prenatal Environment Slide 17 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Effects of drugs are difficult to predict; cant use results on animals and adults for infant development Infants can be harmed by large amounts of medications used in labor and delivery Effects determined by many factors: genetics, mothers health, length of labor, size of baby Slide 18 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Maternal factors may affect unborn child Age and parity Fertility difficulty increases with age Miscarriage and chromosomal damage risks increase with age Older fathers contribute to poor outcomes Teen moms at greatest risk Choice of diet Affected by ethnicity, SES, and education Slide 19 2009 The McGraw-Hill Companies, Inc. All Rights Reserved 25-29 40 60 0 20 30-2445-5040-4420-2435-39 Maternal age (in years) Percent risk of miscarriage Slide 20 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Maternal age (in years) 25304540 1 35 Percent risk of chromosomal abnormality 20 2 3 4 5 0 Slide 21 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Maternal factors may affect unborn child Emotional state of mother Stress during pregnancy and childbirth Social support network can help Fathers support and presence can comfort Experienced support can be effective Slide 22 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Maternal factors may affect unborn child Diseases and disorders: Timing effects outcomes mumps, rubella, Rh factor incompatibility Parasitic and bacterial infections Toxoplasmosis from feces, undercooked meat Slide 23 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Risks in the Prenatal Environment Maternal factors may affect unborn child Parasitic and bacterial infections Bacterial infections from untreated STDs, gonorrhea, syphilis, and chlamydia Viral infections from genital herpes HIV and AIDS up to 25% chance of transmission to fetus during Birth delivery Breast milk feeding Slide 24 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Birth and the Beginnings of Life Birth Most significant event in parents life Labor and delivery is transition for infant Three stages of childbirth Natural childbirth: changed in 19 th century 92% of US births attended by physicians Lamaze method many advantages Cesarean deliveries raise concerns of risk Slide 25 2009 The McGraw-Hill Companies, Inc. All Rights Reserved The Stages of Birth b d a c Placenta Vagina Cervix Uterus Fig. 3-5 Slide 26 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Birth and the Beginnings of Life Birth Birth complications Apgar scoring system Prematurity and low birthweight About 9% are premature births Premature at 37 weeks or less after gestation Average weight is 5 pounds Risks of cognitive deficits Slide 27 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Score 012 Body Color Blue, pale body Body pink, extremities blue Pink all over Heartbeat AbsentSlow less than 100 beats per minute Fast 100 to 140 beats per minute Reflex Irritability No responseSome motionCoughing, sneezing, crying Muscle Tone Limp and flaccid Inactive, weak, some flexion of extremities Good flexion, active motion, strong response Respiratory Effort Breathing for no more than 1 min. Irregular and slowBreathing good with normal crying Apgar Scale Slide 28 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Birth and the Beginnings of Life Preterm or small-for-date babies In US: low birthweight 2x more likely for African American mothers than white mothers Stimulation programs for premature babies Premature babies and parental contact Long-term effects of prematurity Many emotions affecting many relationships More impactful on lower SES families Stress of special needs and coping Slide 29 2009 The McGraw-Hill Companies, Inc. All Rights Reserved 12 0 2 4 6 8 1410 Days 3 lb. 7 oz. (1700 g) 2 lb. 8 oz. (1300 g) 3 lb. 1 oz. (1400 g) 3 lb. 3 oz. (1500 g) 3 lb. 5 oz. (1600 g) Premature infants who received no massage Premature infants who received massage Weight in pounds (grams in parentheses) Slide 30 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Vulnerability and Resilience in Children at Risk Most pregnancies and deliveries normal 10% of all births are anomaly Why vulnerable children develop resilience Environmental characteristics Family skills, income and resources, and personal behaviors Neighborhood and community Caregiving environment Slide 31 2009 The McGraw-Hill Companies, Inc. All Rights Reserved Vulnerability and Resilience in Children at Risk Why vulnerable children develop resilience Biological characteristics Prenatal and perinatal Perceptions, ability to focus, intellectual capacity, motor skills, and behaviors Development deficits can be compounded or compensated by environment and biological factors Slide 32 2009 The McGraw-Hill Companies, Inc. All Rights Reserved The End