1. PSYC 206
Lifespan Development
Bilge Yagmurlu

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

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

4. 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

5. 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

6. 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

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

8. 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

9. 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

10. 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

12. 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

13. 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

14. 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

15. Sensitive periods for teratogens

16. 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

17. 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

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

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

20. 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

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

22. 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

23. 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

24. 24

25. 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

26. 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