Prenatal development

Question 1

what are the stages of embryonic and foetal development?

Answer 1

• ovum (freshly fertilized)
• embryo (4 weeks old)
• foetus (8 weeks old)
• newborn (9 months)

Question 2

what is the 8 week gestation?

Answer 2

• Zygote: first two weeks of life
• Embryo: beginning of 3rd week of gestation until the end of 2nd month

Question 3

what is the 18 week gestation?

Answer 3

• Foetus: from 2-3 months of gestation until birth

Question 4

what is the 24 week gestation?

Answer 4

• Age of viability: period between 22-26 weeks of gestation: foetus’s systems are sufficiently developed (reflexes, can open and close eyes, etc.), so if born prematurely, has good chances of survival
• Premature birth: before full-term gestational period of 37 weeks (full gestation range is 37-41)

Question 5

what is the Prenatal brain development?

Answer 5

• Prenatal brain development in 3rd trimester:
  - Neurons generated at a rate of 250,000 per minute

Question 6

what are Teratogens?

Answer 6

• Any environmental agent that may interfere with the development of the foetus: e.g., maternal…
  
  • Alcohol
  • Smoking
  • Malnutrition
  • Physical health
  • Mental health
    + many others physical and social aspects: pollution, pandemic…
    + The issue of comorbidity (e.g., alcohol + mental health + poor nutrition)

Question 7

what is the role of Maternal malnutrition?

Answer 7

• Mother’s food intake and/or weight gain during pregnancy may affect foetal development
• Studies with children of Dutch women pregnant during the Nazi food embargo (“the Dutch Hunger Winter”):
• extreme undernutrition (fewer than 1000 calories a day) during 1st and 2nd trimesters (= rapid brain reorganisation) associated with risk of schizophrenia, antisocial personality disorder or a mood disorder

Question 8

what is the role of Maternal mental health?

Answer 8

• Depression
  
  • Higher chance of prematurity and low birth weight
• Stress
  
  • Self-reported distress
  • Objectively measured by cortisol
    levels (increase = more stress)
• Natural events (e.g., ice storm: Laplante et al., 2008) with higher objective stress led to lower kids’ IQ at age five
• comorbidity

Question 9

what is Prenatal and transnatal learning?

Answer 9

• Transnatal learning: learning that occurs during the prenatal period which is remembered during the postnatal period
• to detect psychobiological continuities between foetal and infant development
• “Big Question”: if learning already occurs prenatally, can we talk about any innate capacities?

Question 10

what is the link between foetal smell and taste?

Answer 10

• Maternal food alters the “flavour” of amniotic fluid
• Some evidence that broad maternal food selection engenders broad child’s food consumption (but: correlational design)
• Sensitivities to sweet over other tastes
  - Poor at detecting salty tastes, even after birth
• Smell: newborns at 6 days recognise their own mother’s breast milk smell over another mother’s

Question 11

what is Foetal hearing?

Answer 11

• Auditory system is mature enough between 23-25 weeks to detect vibroacoustic stimulation at almost all frequencies (Kisilevsky, 1995):
  
  • Internal noises are heard more easily (mother’s heartbeat and voice)
  • Foetuses respond to external stimuli!
• Heart rate accelerations and body movements:
  ‣ Recognize mother’s voice (Kisilevsky et al, 2003)
  ‣ Discriminate speech sounds (Lecaunet et al., 1987)
  ‣ Discriminate male and female voices (Lecaunet et al., 1993)
  ‣ Sensitive to white noise, frequency and intensity changes, vibrations

Question 12

what is Postnatal auditory perception?

Answer 12

• Newborns prefer listening to mother’s voice (DeCasper & Fifer, 1980)
• Newborns prefer listening to the language they heard in the womb compared to another, foreign language (Mehler et al., 1988; Moon et al., 1993)
• Newborns recognise stories read to them in the womb (DeCasper & Spence, 1986)

Question 13

Method: High amplitude dummy sucking
paradigm

Answer 13

• Baseline dummy sucking rate is determined during a 1-minute silent period
• Presentation of sound stimulus is made contingent on rate of sucking:
  
  • Reaching high-amplitude sucking criterion results in presentation of an auditory stimulus
• Habituation paradigm:
  
  • When infant habituates to stimulus, it changes.
  • Difference in sucking rate in the post-shift period for infants in the experimental vs. control
    conditions is used to assess infant’s sensitivity to stimuli differences

Question 14

what is the evidence for foetal learning of language?

Answer 14

• Mothers read the same book 2x/day for last 6 weeks of pregnancy
• Method: Changes in newborn’s rate of sucking turned on or off a tape recorder of mother reading (half read that story, the other half another story)
• Key finding: Infants modified their rates of sucking in the direction that produced the familiar story
• So what? Evidence for transnatal learning!

Question 15

what is Foetal vision?

Answer 15

• Optic nerve formed by 9 weeks
• Retinal layering in period of 12-28 weeks
• Bright light shone on uterus led to increased heart rate, from 28 weeks
• Eyelids sealed from 8-22 weeks
  - but: can see through eyelids!
• Get more light than previously thought (Del Guidice, 2011)

Question 16

Ultrasound imaging: 4D?

Answer 16

• 3d ultrasound plus movement (the 4th dimension)
• High frequency resonance means limited time for use (British Ultrasound Society)
• Amniotic fluid is needed in front of a face for a reasonable image

Question 17

what is the Foetal response to visual stimuli?

Answer 17

• Orienting more to “face-like” configuration as compared to non face-like configuration of light
• Postnatal experience of faces is not required for this predisposition

Question 18

what are the Newborn face preference studies?

Answer 18

• Head turning gaze direction paradigm
• Newborns can distinguish face from nonfacelike stimuli
• Faces are attended to from birth, with preference for upright more than inverted

Question 19

attention to faces: competing theories?

Answer 19

• Nativist theory: Humans are born with an abstract
  face schema; attractive models/configurations with
  more symmetrical features fit schema better
• Empiricist theory: Preference to faces emerges
  developmentally through associative social learning:
  infants associate a ‘proper’ face of caregivers with
  positive outcomes (e.g., being nursed or cuddled)

Question 20

what are the Physical and motor development?

Answer 20

• Organised embryonic behaviours at 8-12 weeks of gestation:
  
  • expanding and contract lungs, kicking feet, bending arms, forming fists, curling toes, sucking thumb, opening the mouth
• All core physical characteristics are well in place by 7 months
• Remaining physical changes relate to:
  ✓ Increase in fat tissue (including white matter which is crucial for conduction of neuronal impulses)
  ✓ Increase in muscle size

Question 21

what is the Inter-sensorimotor action anticipation?

Answer 21

• Arm and hand movements toward the face were
  examined at 5-9 months of gestation
• More than half of the observed arm movements
  resulted in the hand touching the mouth either
  directly or indirectly
• Movements were anticipatory! Foetuses opened
  their mouths before their hands came in contact
  with their mouths.

Question 22

what is the Newborn motor development?

Answer 22

• Compared to other mammals, human newborns have very poor motor skills
• Head is disproportionately big, about 25% of the total body size – hard to control neck muscles
• Motor development progresses from the head to the rest of the body (but huge individual variability)
• Neonates exhibit a series of reflexes:
  
  • grasping, stepping, sucking, Moro’s

Question 23

what are reflexes?

Answer 23

• Reflexes that remain: breath, rooting, sucking, swallowing
• Reflexes that disappear within 1st year: toe curling, finger grasping/grip, startle, stepping
• Stepping reflex: disappears within 2 months
• “Big questions”: Is it simply a kicking motion or a precursor of early walking?
• Helps in birthing process itself?