Lecture 1 - Prenatal Development Flashcards by Emily Ramsey

Prenatal

Before birth

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Perinatal

Around time of birth

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Three stages of prenatal development

Zygote
Embryo
Foetus

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Risks in Prenatal environment

Teratogen: An environmental agent that causes prenatal damage
Effects during critical/sensitive periods
Effects are specific
Longer exposure is worse
Some have no effect on mother
Maternal/foetal genes may counteract effect
3-8 weeks= most likely major effects, structures being developed
8+= more about function so less likely to be effected, more about brain developing

Prescription Drugs 
Legal Substances 
Environmental Toxins 
Infectious Diseases 
Maternal Factors

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Stages of prenatal development - Zygote

0-2 weeks -> conception to implantation
Ovary-> fillopian tube –> uterus (week)
Unportectected sex, sperm up both-> fertilised in tube, develop in fillopian tubes (zygote)
Sperm in = chemical barrier
Dividing and devloping
Week further to implant

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Stages of prenatal development - Embryo

3-8 wks -> structural development
Neural tube (elongation of ball of cells -> becomes brain & spinal cord
Placenta, Umbilical Cord, Amniotic Sac
Miscarriage risk highest

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Amniotic sac

Fluid-filled membrane protecting embryo

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Placenta

Disc-like structure connecting embryo to uterus

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Umbilical cord

Tube connecting embryo to placenta
Provides oxygen & nutrients
Removes carbon dioxide & waste

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Stages of prenatal development - Foetus

9-38 wks -> functional development 
Brain development 
Responds to stimulation 
Reflexes develop
Brain devlopes most- ceribral cortex and front of brain

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Can tell sex

Wk 12

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Can feel movement

Wk 17-20

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Viability

Can survive outside the womb
wk 22-26
Last few weeks is only development of body fat etc -> temperature regulation (hence need for incubator to do this if premature)

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Teratogens: Prescription Drugs

Thalidomide
Drug for morning sickness (1957-61)
Caused structural abnormalities in limbs & face

DES
Hormone to prevent miscarriage (1947-64)
Linked to reproductive problems & cancers in offspring

Gene dependent

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Teratogens: Legal Substances

Caffeine
Miscarriage, low birth weight (LBW)
Avoid > 200mg

Tobacco
Chemicals in smoke -> miscarriage & prematurity
Nicotine affects placenta -> poor nutrition
-> LBW
Carbon monoxide -> reduce oxygen carrying in baby too

Alcohol
Foetal Alcohol Syndrome (FAS) -> Foetal Alcohol Spectrum Disorder (FASD)

Stunted growth
Physical defects
Often mental retardation 
Wont catch up
Mental impairement perminantly

Alcohol displaces oxygen -> effects baby
Last trimester worst
Brain develops throughout and so can be effected at any time
Guidlines change even for normal drinking now

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Teratogens: Environmental Toxins

Radiation 
Atomic bomb, nuclear reactor meltdowns, ordinary X-ray
Miscarriage
Stunted growth
Physical defects 
Cancer

Pollution 
Lead, mercury, PCBs
Prematurity
LBW
cognitive delays

Teratogens: Infectious Diseases

Most serious -> TORCH

Toxoplasmosis
Parasitic infection in cats -> cleaning litter box and touch excretions
Raw meat
Brain and Eye damage

Other viruses 
HIV/ AIDS - 25% transfer untreated, 1% treated
Mortality
Small head
Physical &amp; mental defects

Rubella
Damages eyes, ears, heart
Mental retardation

CMV
Virus w/ mild (or no) flu-like symptoms
Most common

Herpes
Sexually transmitted virus
Damages eyes, brain, motor system

Zika Virus

Mosquito-borne infection
Uganda (1947) 
2016 epidemic: Asia, South America 
Can cause mild fever in mother 
Infant microcephaly (small brain) 
Infects foetal brain tissue 
No vaccine (yet) 
Lifelong sensory, motor &amp; cognitive disability
Can cause death

Other risks to fetus - maternal factors

Age
Fertility problems increase w/ age
Miscarriage & chromosomal damage risks increase w/ age
Teen mums also at risk -> less likely to get care (want to hide)
Better odds if not first

Nutrition 
Weight gain 
Affected by ethnicity and SES 
Folic acid: Neural tube defects (closes neural tube either end)
Prematurity 
Miscarriage

Prenatal Care

Health
Toxemia/Pre-eclampsia -> Pregnancy-caused high blood pressure -> Restricted growth, preterm birth, stillbirth

(Gestational) Diabetes - High birth weight, preterm birth, temporary breathing problems

Anencephaly

No brain

Dont survive longer than a few day, if doesnt close at the top

Spina Bifida

Doesnt close at the bottom

3x more likely for defect without folic acid

Newborn assessment

APGAR scoring system 
A - Activity (floppy or strong)
P - Pulse (above 100bmp)
G - Grimace (response to extrenal)
A - Appearance (bright pink- oxygen)
R - Respiration (crying = good)

1 and 5 minutes after birth
Measured 0 - 2 points each
Totalled -> 0-3 = severely depressed, 4-6 = moderately depressed, 7-10 = excellent condition

Perinatal Complications: Prematurity

Preterm: < 36 wks 
< 10% births (UK) 
Avg weight 2.3 kg (5 lb) 
Risk of cognitive delay 
Appropriate weight for pregnancy length

Very preterm: < 32 wks

Extremely preterm: < 26 wks
Inadequate surfactant (liquid in lungs that sends O2 into blood)
May cause respiratory distress syndrome

Risk Factors – only evident in half of cases

Surfactant

Breath air as oxygen had been through placenta

Respiratory distress syndrome

Serious breathing complications

Perinatal Complications: Low Birth Weight

Small-for-Date Full-term OR preterm BELOW expected weight for pregnancy length ‘Normal’ birth weight is approx. 3.5 kg (7.7 lb) Could be from nutrition More vunrable to infections and respiratory problems Also link to less good in school, hyperactivity and more Most will physically catch up by 4 but may have motor problems Low Birth Weight (LBW) < 2.5 kg (5.5 lb) Very Low Birth Weight (VLBW) < 1.5 kg (3.3 lb) Extremely Low Birth Weight (ELBW) < 1.0 kg (2.2 lb)

Stimulation Programmes for Preterm Babies

Used to be isolated to protect health But under-stimulation delays development Mimic the sensations of the womb? Skin-to-skin contact (kangaroo care)? Massage? Interact same as if full-term newborn, or is this overstimulating?

The Breathing Bear

Preterm infants Stimulation Programmes for Preterm Babies 33 wks - conceptional age (CA) -> babies randomly assigned to Breathing Bear (BB) or Non-Breathing Bear 35 wks - CA -> 2-hr observation, recording babies’ sleep/wake states (Active sleep, quiet sleep, sleep-wake transition, waking, or fuss/crying) Movements and startles were also measured. BB babies showed less waking, more quiet sleep, fewer startles in quiet sleep, and less crying. BB babies were more likely to smile than grimace during active sleep, whereas NB babies had the opposite pattern.

Parent Interventions

``` Preterm babies need even more sensitive care than full-term babies, but likely to get even less sensitive care due to: Physical appearance High-pitched cry Feeding difficulties Lower responsiveness ``` Hospital or home-based interventions aim to improve parent-infant interaction

Effectiveness of interventions

Depends on: Nature of intervention (e.g., massage, maternal sensitivity, infant self-regulation) Infant characteristics (e.g., how preterm, how stable/healthy otherwise) Intervention duration and/or intensity Length of follow-up (e.g., 6 months, 9 years) Outcome measures (e.g., physical dev., cognitive dev., attention, behaviour problems)