Chapter 2 Prenatal Development and the Newborn Period I Prenatal Development A Conception 1 Epigenesis a Emergence of new structures and functions during development 2 Gametes 3 Zygote a Reproductive cells i e eggs or sperm b Only contain 23 chromosomes no pairs c Created via meiosis a Fertilized egg b 46 chromosomes 23 pairs c Beginning of germinal prenatal stage d Grows via mitosis i Process of duplication and division B Developmental Processes 1 Periods of Prenatal Development a Germinal i Conception up to two weeks ii Ends when zygote attaches itself to the uterine wall iii Rapid cell division takes place b Embryonic i Three to eight weeks following conception ii Major development of the organs and systems of the body c Fetal i Nine weeks to birth ii Rapid growth of the body iii Increasing levels of behavior sensory experience and learning 2 Steps Allowing For Transformation of the Zygote a Cell division i Zygote continually splits into two cells for each existing cell ii Continues for all 38 weeks of gestation i Cell movement from point of origin to designated spots b Cell migration c Cell differentiation i Stem cells d Cell death i cell suicide Apoptosis All embryonic cells initially No specialized function ii Differentiate into 350 types of cells ii Necessary for developmental processes iii e g development of individual fingers of the hands a Genetic material doesn t have a direct effect on development of male or female b Testosterone or lack thereof generated by the fetus itself causes t to become male 3 Role of Hormones genitalia or female C Early Development 1 Twins a Identical twins i Monozygotic ii Inner cell mass splits during early mitosis iii 1 in 250 live births b Fraternal twins i Dizygotic ii As genetically similar as two siblings iii 2 Extra embryonic Supports a Amniotic sac 1 in 30 live births i Transparent fluid filled membrane that protects the fetus in gestation ii Allows fetus to practice using its muscles b Placenta i Nutrient rich blood vessel network ii Allows for transfer of nutrients and minerals iii iv Produces hormones such as estrogen and progesterone Umbilical cord contains blood vessels from placenta to fetus Estrogen increases blood flow to the fetus Progesterone limits uterine contractions that could lead to premature labor 3 Cephalocaudal Development a Phenomenon of areas near the head developing before areas further away D Fetal Behavior 1 Movement a Fetus begins to bend its head at 5 or 6 weeks b Hiccups begin at 7 weeks c All movements present at birth are present at 12 weeks d Fetal breathing i Breathing in swallowing of amniotic fluid ii Practiced beginning at 10 weeks iii Only occurs 50 of the time iv Helps develop digestive system 2 Behavioral Cycles a Fetus only moves 10 30 of the time during the second half of pregnancy b When nearing birth fetuses spend almost all of their time in REM sleep E Fetal Experience 1 Sight 2 Touch 3 Taste 4 Smell 5 Hearing a Very little to see b 26 weeks can experience changes in light a Fetus can explore its own body and its environment a Fetuses prefer sweet tastes as opposed to standard amniotic fluid a Amniotic fluid absorbs the odors of whatever the mother has recently consumed b When fetus swallows the fluid he she can smell whatever is in it a Starting to develop at end of 2nd trimester b Fetus can hear some external sounds i People talking to the mother ii Mother s voice Internal sounds 75 Db i Mother s heartbeat ii Mother s breathing iii Vascular system iv Mother s digestive tract c a Vestibular system developed at 5 months 6 Motion F Fetal Learning 1 Fetuses are able to learn once their central nervous system develops 6 months a Able to distinguish between noises and become habituated to repeated stimuli Infants prefer familiar sounds scents and tastes 2 Preferences a b Preferences are persistent 3 Heartbeat Experiment 1970s a Group 1 normal maternal heartbeat b Group 2 fast maternal heartbeat c Group 3 no heartbeat d Results i Group 1 Group 3 Group 2 in terms of babies response to normal heartbeat 4 Maternal Vocal Learning a Pregnant moms read The Cat in the Hat twice day for six weeks b Newborns changed sucking rate to turn on familiar or novel story i Newborns wanted to hear familiar story 5 Prenatal Learning a Prenatal education programs including the following do not work i Learning books through excessive reading ii Recognizing Daddy s voice by using a megaphone iii Learning music through excessive listening b Baby may only develop preferences for mother s voice c Baby will quickly recognize Dad s voice after birth anyway G Hazards to Prenatal Development 1 Environmental Influences a Minamata disease i Methyl mercury poisoning ii Lead to Human illnesses Bizarre behavior in cats Intellectual disabilities cerebral palsy seizures blindness deafness Caused by local seafood iii i Chemical agents that infiltrate the fetus vascular system and lead to damage b Teratogens or death c Sensitive period i Period of time in which the fetus is the most sensitive to harmful teratogens ii Different for various parts of the body iii Most sensitive periods begin before a woman might realize she is pregnant d Prospective longitudinal PL design i Initial measure at or before birth ii Study effects of conditions far into future e Dose response relation i Greater exposure to a harmful substance leads to greater effect and damage on i Delayed emergence of the effects of the prenatal environment i A side effect of an agent that lies dormant for a long period of time following the child f Fetal programming g Sleeper effects birth h Legal Drugs i Cigarette Smoking Fetus receives less oxygen Fetus may metabolize cancer causing agents in tobacco Consequences 13 of women smoke during pregnancy Delayed growth Low birth weight ii Alcohol Most common human teratogen 15 20 of women drink during pregnancy Blood levels in mother and child are equal but fetus has lower ability to remove alcohol from blood Fetal Alcohol Spectrum Disorder FASD Fetal Alcohol Syndrome Autism Spectrum Disorder symptoms Attention deficits Hyperactivity Fetal Alcohol Effects Similar but less severe symptoms i Illegal Drugs i 4 of pregnant women use illicit drugs ii Marijuana most common followed by cocaine iii Consequences Impaired attention Fetal growth retardation Premature birth Withdrawal from drug j Environmental Pollutants i PCBs lead to Smaller head circumference Slightly lower than average IQ scores ii Mercury Minamata disease Grain