Comprehensive Study Notes: Prenatal & Newborn Development (Transcript-based)

CULTURAL VIEWS OF PRENATAL DEVELOPMENT

  • Tradition and lore worldwide; greatly influence beliefs about pregnancy and development.
  • Biggest debates in modern society: e.g., when does life begin? (heavily influenced by culture).
  • Western views vs. the Beng (as highlighted in the transcript).
  • Conception: zygote → embryo → fetus; emphasizes the developmental process.

GAMETES AND CONCEPTION

  • Gametes: reproductive cells – egg and sperm – that contain half the genetic material of all the other cells in the body.
  • Each gamete contains one member from each of the 23 chromosomes.
  • Meiosis: cell division that produces gametes.
  • Pathway: Ovaries → fallopian tube → uterus (site of possible conception).
  • Conception: union of an egg from the mother and a sperm from the father.

ZYGOTE, EMBRYO, FETUS

  • Zygote: a fertilized egg cell.
  • Embryo: developing organism from the 3rd to the 8th week of prenatal development.
  • Fetus: developing organism from the 9th week to birth.
  • Process from zygote to embryo to fetus involves: division, migration, differentiation, death (apoptosis).

DEVELOPMENTAL PROCESS

  • Cell Division: Mitosis – cell division that results in two identical cells; begins about 12\text{ hours} after conception.
  • Cell Migration: newly formed cells move away from where they were created.
  • Cell Differentiation: embryonic stem cells can become more than 200 possible cell types.
  • Cell Death: Apoptosis – genetically programmed cell death; follows a pre-programmed timeline.

EARLY DEVELOPMENT

  • FIRST 4 WEEKS: support systems, processes, and major milestones.
  • FIRST WEEK:
    • On day 4 after conception, cells form the ‘inner cell mass’.
    • Identical (monozygotic) twins result from splitting of the zygote (same genes).
    • Fraternal (dizygotic) twins occur when two eggs are released and fertilized by two different sperm; share ~50% of genes.
    • Inner cell mass → embryo; remaining cells → placenta and amniotic sac.
  • 2nd WEEK: LAYERS FORM
    • Inner cell mass folds into three layers:
    • Top layer: nervous system, nails, teeth, inner ear, lens of the eyes, outer surface of the skin.
    • Middle layer: muscles, bones, circulatory system, inner layers of the skin, internal organs.
    • Bottom layer: digestive system, lungs, urinary tract, glands.
    • A U-shaped groove forms down the center; Neural tube forms → brain and spinal cord.

SUPPORT STRUCTURES

  • Amniotic sac: a transparent, fluid-filled membrane surrounding the fetus; provides protection, temperature regulation, cushioning.
  • Placenta: a semi-permeable support organ; keeps circulatory systems separate (prevents Rh incompatibility); defensive barrier is not perfect.
  • Umbilical cord: tube containing blood vessels connecting fetus and placenta.

PRINCIPLES OF DEVELOPMENT

  • Earlier development occurs at a more rapid pace than later development.
  • Cephalocaudal development: development occurs head-to-tail; areas nearer the head develop earlier than those farther away.
  • The key idea: FAST → slow progression over time.

TRIMESTER WEEKS: MAJOR MILESTONES

  • 1st trimester (weeks 1–12):
    • Zygote travels from fallopian tube to womb and embeds in uterine lining; cells arrange into a ball and begin to form embryo and support system.
    • Embryo forms three layers; neural tube develops; primitive organs begin forming.
  • Weeks 4: neural tube develops into brain and spinal cord; primitive heart visible; limb buds appear.
  • Weeks 5–9: facial features differentiate; rapid brain growth; internal organs form; fingers and toes emerge; sexual differentiation begins.
  • Weeks 10–12: heart develops its basic adult structures; spine and ribs develop further; brain forms major divisions.
  • 2nd trimester (weeks 13–24): lower body growth accelerates; external genitals fully developed; body develops hair; fetus can make basic facial expressions; fetal movements felt by the mother.
  • 3rd trimester (weeks 25–38): fetus triples in size; brain and lungs sufficiently developed (~28 weeks) for survival outside the womb; visual and auditory systems functional; learning and behaviors begin to emerge.
  • Source: Siegler et al., 2020.

FETAL EXPERIENCES

  • The 5 senses in the womb and early learning.

MOVEMENT & TOUCH

  • Movement begins around 5-6\text{ weeks} onward.
  • Reflexes: hiccups, burping, swallowing amniotic fluid (contributes to digestive and palate formation).
  • Fetal breathing begins in the 3rd trimester (approx. 1\text{ breath per second}).
  • Touch: grasping the umbilical cord, thumb-sucking, and face rubbing; thumb preference may predict handedness.
  • Fetuses respond to mother’s movements via the vestibular system.

SIGHT, TASTE, & SMELL

  • Sight: minimal in womb; by the 3rd trimester, simple visual patterns (e.g., face-like shapes).
  • Taste: amniotic fluid carries flavors; fetuses prefer sweet tastes (increased swallowing with sugar solution).
  • Smell: odors from mother’s diet transmitted through the amniotic fluid; perceived via fetal breathing.

HEARING & EARLY LEARNING

  • Womb is noisy: heartbeat, digestion, blood flow.
  • Mother’s voice is especially prominent; increased heart rate when mother speaks.
  • Sound is a dominant channel for prenatal learning.

LEARNING IN THE WOMB

  • Fetuses remember auditory experiences (melodies, voices).
  • Key processes:
    • Habituation: decreased response to repeated stimuli.
    • Dishabituation: new stimulus rekindles interest after habituation.
  • Habituation appears as early as around 30\text{ weeks gestational age (GA)}.
  • Preferences extend to taste and smell; maternal diet influences cultural food preferences.

PARTANEN ET AL. (2013): AT A GLANCE

  • EEG (electroencephalography): time-sensitive, non-invasive method measuring brain electrical activity via scalp electrodes.
  • ERP (event-related potentials): measured brain response directly resulting from a specific event.
  • Question: Does prenatal music exposure leave lasting neural traces?
  • Design: Parents played "Twinkle Twinkle" ~5x/week from 29\text{ wks GA} to birth; infants tested at birth & 4 months using EEG.
  • Key Result: Exposure group showed stronger neural responses; more plays → stronger effect.
  • Persistence: Effects lasted to 4 months without extra training.

HAZARDS TO PRENATAL DEVELOPMENT

  • Categories: MISCARRIAGE (spontaneous abortion); TERATOGENS (drugs & environment).

MISCARRIAGE (SPONTANEOUS ABORTION)

  • Usually very early in pregnancy (before detection).
  • Main cause: incorrect chromosome number.
  • Canada & US → approximately 6\% - 15\% of reported pregnancies; likely higher in reality (~25\% - 50\% experience at least one miscarriage).
  • About 1\% of women experience recurrent miscarriage (more than 3 in a row).

TERATOGENS & SENSITIVE PERIODS

  • Teratogen: external agent that can cause damage or death during prenatal development.
  • Sensitive period: time during which a developing organism is most sensitive to external factors.
  • Example: Thalidomide (morning sickness drug in the 1950s–60s) caused severe limb deformities when taken during weeks 4-6.

PRINCIPLES OF TERATOGEN EFFECTS

  • Dose-response relationship: the effect of exposure increases with the extent of exposure; more exposure = more severe effects.
  • Combination of teratogens complicates outcomes; difficulty isolating the effect of each factor.
  • Poverty can involve multiple risk factors (nutrition, stress, toxins); multiple risk factors have a cumulative impact.
  • Individual genetic susceptibility leads to variability in outcomes.

DRUGS AS TERATOGENS

  • Drug use in Canadian mothers: around 6.7\% before pregnancy/realization; about 1\% after realizing they were pregnant (Public Health Agency of Canada, 2009).
  • Categories include: drugs of abuse (legal & illegal) and some prescriptions/OTC drugs.

ANTIDEPRESSANTS & OPIODS

  • Antidepressants: treat depression; may reduce risk of postpartum depression (rates of postpartum depression \approx 10-30\%); fetal risk evidence is inconclusive.
  • Opioids: prescription or illicit; mimic neurotransmitters and disrupt brain development; can lead to NAS (neonatal abstinence syndrome) including low birth weight, breathing and feeding issues, and seizures.

MARIJUANA & CIGARETTES

  • Marijuana: rising use with legalization; data are inconclusive; combined with tobacco increases risk; interaction effects exist [Ryan et al., 2018].
  • Cigarettes: consequences include low birth weight, slowed growth, increased risk of SIDS, lower IQ, hearing deficits, ADHD, cancer.
  • Dose-response relationship; timing matters; greatest risk during the first trimester.
  • About 12\% of pregnant Canadian women smoke during pregnancy; e-cigarettes: nicotine still a risk.

ALCOHOL

  • Leading cause of fetal brain injury.
  • About 1}{10} pregnant Canadian women drink; alcohol crosses the placenta, leading to fetal blood-alcohol levels similar to maternal levels.
  • FASD: fetal alcohol spectrum disorder – includes Fetal Alcohol Syndrome (FAS): facial features, intellectual disability, attention problems, hyperactivity.
  • Canadian prevalence of FASD: about 2-3\%.

ENVIRONMENTAL TERATOGENS

  • Metals, plastics, pesticides, hormones; air pollution linked to low birth weight and neurotoxicity.
  • Disproportionate impact on low-income families.
  • Case example: Grassy Narrows and White Dog First Nations (Ontario) – mercury dumped in river leading to long-term poisoning; Minamata disease as a related reference.

MATERNAL FACTORS - OVERVIEW

  • Age:
    • Teen pregnancy (< 15\text{ years}) associated with increased infant mortality.
    • Older mothers (30-40\s+yrs) associated with increased developmental disorders.
  • Nutrition: inadequate diet and folic acid deficiency associated with birth defects (e.g., spina bifida).
  • Disease: rubella, CMV, herpes, HIV, Zika.
  • Mental health: stress affects cognitive development and later psychiatric diagnoses.

MATERNAL NUTRITION

  • Nutritional deprivation leads to fetal deprivation.
  • Folic acid is critical (fortified foods, prenatal vitamins).
  • Poverty confounds: multiple risk factors.
  • WWII Dutch famine as a case study; impacts include impaired attention and prematurely aged brains.

MATERNAL DISEASE

  • Illnesses such as rubella can cause deafness, blindness, intellectual disability.
  • STIs include CMV (50-70% of women of reproductive age); most common cause of congenital infection with CNS damage and hearing loss.
  • Genital herpes can cause blindness or death if transmitted at birth.
  • HIV: transmission possible but uncommon.
  • Zika: microcephaly in up to 6\% of fetuses; associated learning difficulties, seizures, hearing/vision loss; sensitive period mainly during the 1st trimester.

MATERNAL MENTAL HEALTH

  • Prenatal stress affects infant cognition and later psychiatric diagnoses.
  • Wealthier countries: minority groups more affected; less wealthy countries: higher overall stress due to resource scarcity and higher infant mortality.
  • Links to multiple risk factors; difficult to disentangle.
  • Required reading cited: Rice et al., 2010 (IVF design).

RICE ET AL. (2010): AT A GLANCE

  • Question: Do prenatal stress effects reflect environmental vs. inherited factors?
  • Design: IVF-related vs. unrelated mother-child pairs (cross-fostering logic).
  • Key results:
    • Birth weight & gestational age: seen in both groups → environmental factors.
    • Antisocial behavior: both groups → environmental factors.
    • Anxiety: reduces after current maternal anxiety/depression → postnatal confound.
    • ADHD: only related → inherited factors.
  • Takeaway: Different outcomes map to different pathways.

BIRTH EXPERIENCE

BIRTH EXPERIENCE – SAME BIOLOGY, DIFFERENT PRACTICES

  • Birth biology is similar worldwide, but practices surrounding childbirth vary widely.
  • Two main goals: survival/health and social integration.
  • Balance of these goals leads to different traditions and practices (e.g., Bali vs. North America).

EVOLVING PRACTICES: C-SECTIONS & BIRTH SETTINGS

  • Cesarean (C-section) rates around 28\% in Canada; rates influenced by complications, multiple births, scheduling.
  • Home vs. hospital births; trade-offs in safety, support, access.
  • Ontario statistics: home births occur at a certain percentage (noted as a blank in the source: __%).
  • Trend toward hybrid models (midwives/doulas) with safer emergency backup.

NEWBORN STATES

  • Sleep and cry states define infant arousal levels.

NEWBORN STATES: WHAT "STATE" MEANS

  • State determines what you can notice, do, learn, and think about; also how others can interact with you.
  • Two primary newborn states in early weeks: sleeping and crying.

INFANT SLEEP: AMOUNT & PATTERN

  • Newborns sleep a lot; sleep declines over year 1.
  • Sleep pattern: about 50\% REM sleep initially, declines to 20\% by age 3–4.
  • REM sleep: active sleep with rapid eye movements; traditionally linked to dreaming in adults.
  • Non-REM sleep: quiet/deep sleep with slower brain activity, regular breathing, and heartbeat.

WHY SO MUCH REM? & NIGHT WAKING

  • Theories for high REM in newborns: visual system development, sensorimotor map building via myoclonic twitches, and learning during sleep (brains stay receptive).
  • Nighttime awakenings: typically diminishes over year 1.
  • At 6 months, about ~1/3 wake at least once per night; at 12 months, about 50\% sleep > 8 hours.

CRYING: COURSE & PREVENTION OF HARM

  • Common reasons: illness, pain, hunger, need for contact.
  • Crying peaks at around 6-8\text{ weeks}; declines by 3-4\text{ months}.
  • Risk: abusive responses (e.g., shaken baby syndrome); parental education helps reduce risk.
  • Example: Period of PURPLE – outreach program in BC reducing ER visits and infants admitted with abusive head trauma.

NEGATIVE OUTCOMES

NEGATIVE OUTCOMES: KEY TERMS

  • Apgar score: a quick method for evaluating newborn health immediately after birth based on skin tone, pulse rate, facial response, arm/leg activity, and breathing.
  • Infant mortality: death within the first year after birth.
    • Canada (2018): about 4.5\text{ deaths per 1000 live births}.
    • Absolute rate is improving, but relative ranking globally is declining; variation by province/territory; access and social determinants matter.
    • In less developed countries, rates can be as high as 1\text{ in }10 due to war, famine, and extreme poverty.

LOW BIRTH WEIGHT (LBW): DEFINITIONS & PREVALENCE

  • Typical Canadian newborn weight: 2500\text{ g} \ 4500\text{ g}.
  • LBW: birth weight < 2500\text{ g}.
  • Premature: birth at 37\text{ weeks} or earlier.
  • Canada LBW prevalence: about 7.8\% of babies; Small for gestational age (GA): 6.7% LBW.
  • Medical implications: increased risk of medical complications, neurosensory deficits, frequent illness, lower IQ, and lower educational achievement.

LBW: CAUSES & OUTCOMES

  • Causes: teratogens, airborne pollution, multiple births (fertility drugs, IVF).
  • Around 54\% of multiples are LBW (Statistics Canada, 2019c).
  • Outcomes include: medical complications, neurosensory issues, lower average IQ/achievement, increased odds of ADHD/ASD (Johnson & Marlow, 2011).
  • Brain correlates: reduced white matter, ventricular enlargement; confounded with SES.
  • Most LBW children eventually reach normal ranges, but risk remains.

WHAT HELPS: CONTACT & CARE ENVIRONMENTS

  • Parent-infant contact matters for LBW outcomes.
  • Kangaroo care (skin-to-skin) decreases mortality; increases growth, breastfeeding, and attachment.
  • NICU experiences shape later touch responses; gentle touch elicits stronger positive neural responses.
  • Repeated painful procedures can lead to blunted responses.
  • Care burden and risk: LBW infants can be harder to soothe, increasing caregiver stress and risk of abusive patterns.

MULTIPLE RISK MODEL & RESILIENCE

  • Risks tend to cluster: poverty, pollution, stress, substance use; more risks = worse odds in a non-linear way.
  • Structural factors: low SES, structural racism create access and exposure gaps.
  • Developmental resilience: successful development despite multiple hazards; influenced by personal factors (e.g., self-regulation) and at least one responsive caregiver.
  • Example: English families with four or more risk factors show markedly higher risk; Ritter et al., 1979 reported that one risk factor increases risk modestly, while four or more risks increase risk nearly 10x.