Prenatal Development

Question 1

stages of prenatal development

Answer 1

• Germinal (0-2 weeks): Conception to implantation
• Embryonic (3-8 weeks): Organ development
• Fetal (9 weeks-birth): More development; sensory experiences and learning

Question 2

fetal movement milestones

Answer 2

• movement development affects psychological development
• fetus begins to move at 5-6 weeks gestational age (bends head and spine)
• Hiccups begin around 7 weeks gestational age -> tells us that infant’s respitory system is developing
• By 10 weeks, a clear active vs. Rest cycle has emerged (different than, but mimics sleep vs. Rest cycle in newborns -> longer rest periods closer to birth -> creates a U-shaped curve -> little sleep early on, most sleep around birth, less sleep as life goes on)
• Most birth movements by 12 weeks gestational age

Question 3

gestational age

Answer 3

time since last menstrual period -> conception is estimated based on this date

Question 4

fetal experience/sensation

Answer 4

• Womb is not a vacuum -> fetus has experiences in utero

- includes taste/smell, hearing, touch, and sight

Question 5

fetal gustation/olfaction

Answer 5

• Evidence that fetuses can taste/smell in utero
• 3-day-old neonates turn their heads longer toward familiar (mom’s) vs. Unfamiliar (random person’s) amniotic fluid -> shows they can differentiate
• Moms that eat a certain substance (ie. Ginger) have babies who show a preference for that substance in early childhood

Question 6

fetal audition

Answer 6

• Most of their auditory experience is exogenous
• Much more robust than fetal vision -> when baby is born, auditory system is much stronger and more developed than visual system
• Hearing is transferred mostly internally through mother’s bones
• Fetal heartbeat changes in reaction to external voices
• Fetal heartbeat is different in reaction to music and speech
• Newborn babies (a few minutes old) can recognize their mother’s language and their mother’s voice
  Infants treat a native language differently than they treat a foreign language (as shown by study using suck bursts)

Question 7

fetal vision

Answer 7

• What is there to see in utero?
• Not much -> studies show that light does not penetrate the uterus -> it’s quite dark in utero (not much exogenous experience, most of it comes from endogenous stimulation)
• Retinal ganglion cells (type of neuron in retina) fire irregularly by 22 weeks gestational age (provides endogenous visual experience)

Question 8

exogenous vs. endogenous stimulation

Answer 8

• Exogenous stimulation = stimuli generated by something/someone other than the organism itself
• Endogenous stimulation = stimuli generated by the organism itself

Question 9

fetal learning

Answer 9

• Just like infants after birth, fetuses experience learning in utero
• How do we know?
• Preferences
• Habituation

Question 10

teratogens

Answer 10

• Not everything that the fetus experiences in utero is positive for its development
• One of the most widespread causes of fetal abnormalities is the presence of teratogens – external agents that cause damage or death during prenatal development
• Teratogens most affect fetuses during a series of cascading sensitive periods (shown in graph)
• ex. smoking, alcohol, anti-depressants

Question 11

smoking

Answer 11

• Smoking during pregnancy is detrimental to the fetus in two main ways:
• Metabolizing the carcinogenic chemicals from mother’s bloodstream into fetus’ bloodstream
• Reduction in oxygen intake -> both from mom’s bad lungs and the smoking itself -> results in slow fetal growth and low birth weight

Question 12

alcohol

Answer 12

• Most common and preventable teratogen
• Enters the fetal blood stream without being processed by the mother’s liver -> fetus is getting raw alcohol
• Fetuses are less able to metabolize alcohol than their mothers are -> due both to low tolerance and potentially (depending on where they are in development) may not have enzymes required to break down alcohol
• Alcohol mostly effects women with high education and high SES, which is unlike other teratogens (others mostly affect women with low SES)
• can result in Fetal Alcohol Spectrum Disorder

Question 13

fetal alcohol spectrum disorder

Answer 13

• Most severe complication from alcohol consumption during pregnancy
• Facial deformities are common (ie. Low nasal bridge, minor ear abnormalities, thin upper lip, indistinct philtrum)
• Intellectual disability (IQ scores lower than 70)
• Damage to prefrontal cortex (which controls inhibition and attention) -> Behaviour disorders and Attention disability

Question 14

anti-depressants

Answer 14

• One study examined how antidepressants affect fetal sound discrimination
• part 1: Fetuses tested at 36 weeks to see whether they could differentiate between “da” vs. “ta” sounds (habituation using heart rate)
• Non-SSRI babies can’t discriminate, SSRI babies can (unlike typical babies)
• part 2: follow up at 6 months with non-native french vowels
• Non-SSRI can discriminate, but the SSRI babies could not (again, unlike typical babies) -> shows an advancement of sensitive period for learning language in SSRI babies -> may or may not be bad, too early to tell. May impede speech/language ability

Question 15

perceptual narrowing

Answer 15

• 6-month-olds are good at discriminating those vowels from a language other than their own, but 10-month olds aren’t good anymore -> our ability decreases as we age
• anti-depressant use while pregnant may speed up perceptual narrowing

Question 16

teratogen sensitive periods

Answer 16

• Sensitive periods early on (before 12 weeks/fetal period: CNS, Heart, Arms, Eyes, Legs, Teeth
• Sensitive periods later (after 12 weeks/fetal period): Palate, external genitalia, ear)
• Affected only early on: Heart, Arms, Legs
• Affected in both embryonic/fetal: CNS (throughout whole development), Eyes, teeth, palate, genitals, ears