PSYC 206 Lifespan Development Bilge Yagmurlu

Chapter Overview The Periods of Prenatal Development Environmental Conditions and Prenatal Development Teratogens: Sources of Birth Defects 2

The Period of Prenatal Development Divided into three broad periods: Germinal Period Embryonic Period Fetal Period 3

Germinal Period Begins at conception Lasts until implantation Implantation: process by which the organism becomes attached to the uterus 8 to 10 days after conception Cell division: From a single cell to hundreds of cells 4

Embryonic Period Begins at implantation Lasts until the 8th week Cell differentiation: all major organs have taken shape. Organogenesis Placenta Acts as a barrier that prevents the bloodstreams coming into direct contact Acts as a filter that allows oxygen and nutrients be exchanged 5

Fetal Period Begins at the 9th week Lasts until birth Growth in weight and length Brain and all organ systems increase in complexity Existing structures are refined By 15 weeks the fetus exhibits all movements observable at birth. 6

Fetal Period Basic sensory capacities developing Example: sensing motion, light, sound 7

Characterizing the fetus & its experience Movement ~ 5wks Sensory experience Smell: Amniotic fluid has odor of what mom ate; During fetal breathing, amniotic fluid comes into contact with olfactory receptors Hearing: Internally generated sounds (mom’s heartbeat, breathing, etc.); Externally generated sounds (mom’s voice and people talking to her); Fetus moves & shows heartbeat changes Touch: Grasping, sucking, rubbing, bumping walls of uterus Taste: Swallows amniotic fluid Fetus has a sweet tooth Sight: Negligible

Fetal Period Fetal learning Example: work by DeCasper and Spence (1986) DV: sucking rate IV: “Cat in the Hat” vs. new story Conclusion: prefer the familiar 9

Stages of Prenatal Development Germinal period Zygote Embryonic period Embryo Fetal period Fetus Implantation to Organogenesis +6 weeks Organogenesis to Birth +30 weeks Conception to Implantation 2 weeks

Environmental Conditions and Prenatal Development Maternal factors (age, nutrition, stress, disease, etc.) Teratogens: Environmental agents that increase risk of deviation in normal development, can lead to abnormalities or death 12

Teratogens Common Teratogens: Effects can vary considerably Drugs Including prescription drugs, caffeine, tobacco, alcohol, marijuana, cocaine, and heroin Infections (including rubella and HIV) Radiation or pollution at high levels Effects can vary considerably 13

Teratogens Dose-response relationship (length & amount of exposure determine degree of harm) Many harmful agents cause damage only if exposure occurs during a sensitive period Effects are not uniform: significant individual differences in susceptibility Sleeper effects 14 14

Sensitive periods for teratogens

Teratogens Fetal Alcohol Syndrome (FAS) A set of symptoms that includes an abnormally small head and underdeveloped brain, eye abnormalities, congenital heart disease, joint anomalies, and malformations of the face 16

Teratogens: immediate vs. sleeper effects Alcohol Fetal alcohol syndrome (FAS) Low IQ Poor attention Hyperactivity Slow physical growth If no FAS Attention-deficit hyperactivity problems Cigarettes Low birth weight Less attentive to sounds Low IQ Cancer Illegal Drugs Prematurity Low birth weight Physical defects Breathing problems Addicted at birth Difficult to care for

Gene-environment interactions There’s no safe amount! Individual differences in susceptibility Set of genes control the way each of us metabolize alcohol

Teratogens: Environmental Sources of Birth Defects Cranio-facial abnormality Cerebral cortex size

Individual differences in susceptibility Romitti et al., 1999 DV: Oral cleft defects Predictors: Child’s genes Mother’s smoking & alcohol consumption Incidence 1 in 1000 live births Smoking-alcohol increases incidence at least 2-3 fold Genetic markers and smoking-alcohol increases incidence 3-6 fold

Conclusion Clearly prenatal development not simply biologically pre-programmed Environmental events and biology interact to determine developmental outcomes INTERACTIONIST VIEW

The Newborn’s Condition Assessing the Baby’s Vitality The Apgar Scale Physical condition Brazelton Neonatal Assessment Scale Behavioral condition Primary Goal: Screen for infants at risk Secondary Goal: Predict aspects of future development 22

Physical Condition The Apgar Scale Assesses physical condition Factors rated: Heart rate Respiratory effort Muscle tone Reflex responsivity Color A low score requires immediate medical attention 23

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Behavioral Condition Brazelton Neonatal Assessment Scale Assesses subtle aspects behavior Includes tests of: Reflexes Motor capacities Muscle tone Responsiveness to objects and people Control of own behavior 25

Problems and Complications Prematurity Birth before the 37th week Immature lungs, digestive, or immune systems Low Birth Weight Below 2500 grams Intrauterine growth restrictions 26