Chapter 3 Prenatal Development Nature v Nurture OR BOTH o Much of prenatal development is highly canalized however there are environmental influences on the developing organism Teratology the study of birth defects o Teratology is a science of risk analysis o Prenatal Environmental Influences Teratogens Teratogens harmful agents to the developing organism Examples diseases e g rubella lifestyle choices e g drug use high stress environments medications toxins Prenatal Environmental Influences Teratogens o Determining risk Age Timing of exposure Critical Sensitive period is the time of greatest vulnerability for each body structure Amount of Exposure Dose Heredity Genetic vulnerability Larger doses over longer time periods leads to more negative effects Ethnicity sex males at greater risk Ex Spina bifida more common in Irish and English Ex poor nutrition lack of medical care over exercising Other negative influences Sensitive Periods in Prenatal Development o Teratogens Drugs Prescription o Thalidomide o Accutane Sedative prescribed in 1960s to alleviate morning sickness Caused severe limb deformations when taken by mothers between 4 and 6 weeks Can a Thalidomide Like Tragedy Occur Again Accutane vitamin A derivative prescribed to treat severe acne toxic to developing organisms Causes extensive damage to fetus Ex abnormalities to eye ear skull brain heart CNS immune system Synthetic hormone prescribed between 1945 and 1970 to prevent miscarriage Cause unusually high rates of vaginal cancer malformations of the uterus infertility and premature birth in the daughter of the mothers taking it o DES diethylstilbestrol Nonprescription Illegal o Aspirin o Caffeine o Cocaine o Meth o Heroine o Marijuana Low birth weight infant death lower IQ Low birth weight miscarriage withdrawal for infants Only 1 2 of American newborns exposed ALL OF THE ABOVE premature low birth weight death breathing problems addiction at birth learning disabilities deformalities Smaller head size sleep attention memory disorders academic difficulties depression Tobacco Alcohol Cuts off about 20 of the oxygen to the fetus Low birth weight miscarriage premature birth breathing difficulties asthma cancer impairments of the heart Immediate positive results of the woman stops smoking at any time during the pregnancy Fetal Alcohol Spectrum Disorder FASD o Children with FASD are given one of 3 diagnoses Fetal Alcohol Syndrome Fetal alcohol syndrome Partial fetal alcohol syndrome p FAS Alcohol related neurodevelopmental disorder ARND o Caused by heavy drinking more than 5 drinks day o Causes severe cognitive physical and behavioral difficulties o Is the leading behavioral cause of mental retardation o Facial abnormalities Thin upper lip Smooth or flattened philtrum Short eyelid opening Alcohol produces its harmful effects in two ways o Interferes with cell duplication and migration in the primitive neural tube o Requires large amounts of oxygen to metabolize which draws away the oxygen that the developing organism needs for cell growth Radiation Miscarriage underdeveloped brain slow growth and development Causes severe harm to the fetus Ex nuclear power x rays atomic bombs higher rates of cancer lower IQs Pollution The Effects of Environmental Pollution o More than 75 000 chemicals are in common use in the United States and many new pollutants are introduced each year o Many babies are born polluted by chemicals that can impair development and increase the chances of life threatening diseases and health problems later on Infectious Disease Physical miscarriage mental malformations retardation low birth weight and prematurity Prenatal Development and Later Health o Low Birth Weight Greater chance of heart disease stroke diabetes o Birthweight The average weight of a newborn is 7 lbs Low birth weight LBW is considered less than 5 lbs Preterm is less than 35 weeks o Possible Causes of LBW Lifestyle choices Maternal malnutrition Multiple births Unknown causes Maternal Factors in Healthy Prenatal Development Prescription drugs Ex cigarette smoking accounts for 25 of LBW births worldwide o Exercise o Nutrition Healthy physically fit regular moderate exercise related to increased birth weight Vigorous extended exercise especially late in pregnancy lower birth weight Prenatal malnutrition first trimester miscarriage or physical defects Damage to CNS and structures of liver kidneys pancreas other organs Suppressed immune system development Prenatally malnourished babies often are irritable unresponsive to stimulation and experience long lasting learning problems o Prevention and Treatment o Rh Blood Factor o Age o Emotional Stress Most common blood incompatibility problem Rh factor incompatibility Rh protein is present in blood of the fetus but not in the mother s blood Mother forms antibodies to the foreign Rh protein can return to fetus system Stress hormones cross the placenta causing a dramatic rise in fetal heart rate and activity Fetal neurological functioning can be permanently altered Maternal emotional stress predicts Anxiety short attention span anger aggression and overactivity among preschoolers and young children above and beyond the impact of other risk factors Stress related prenatal complications can be greatly reduced when mothers receive the support of family members and friends
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