Prenatal development and birth Flashcards by Batho Dihemo

how many weeks is a zygote?

0-2 weeks

conception to implantation

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stages of prenatal development: Embryo

4 temporary organs

3-8 weeks: structural development
* neural tube: becomes brain & spinal cord
* amniotic sac: fluid-filled membrane protecting embryo
* placenta: disc-like structure connecting embryo to uterus
* umbilical cord: cord connecting embryo to placenta
provides O2 & nutrients
removes CO2 & waste
* miscarriage risk highest

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stages of prenatal development: foetus

9-38 weeks: functional development
*birth development
* responds to stimulation
* wk 12: can tell sex
* reflexes develop
* wk 17-20: mother feels movement
* wk 22-26: viability

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what are the risks in prenatal development

6 risks

teratogen: 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 effects

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types of teratogens

thalidomide
DES

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teratogens: thalidomide

effects on 6 different days

thalidomide - when started affected outcome. first taken
* day 20 - central brain damage
* day 21 - eye abnormalities
* day 22 - ears/face abnormalities
* day 24 - the arms
* day 28 - leg damage
* day 42 + - no ill effects

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teratogens (legal substances): caffiene

miscarriage, LBW
avoid > 200mg

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teratogens (legal substances): tobacco

chemicals in smoke - miscarriage & prematurity
nicotine affects placenta - poor nutrition - LBW
role of O2
potential ADHD

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Roza et al. 2007 study on tobacco effects:

2 conclusions

affects head circumference
affects biparital measurement

BPD - from skull bone to skull bone

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teratogens (legal substances): alcohol

Foetal alcohol syndrome (FAS):
- stunted growth
- physical changes
- often mental retardation
  - foetal alcohol spectrum disorder (FASD)
- role of O2
- last trimerster worst

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foetal alcohol syndrome in the UK stats:

17% of UK children have symptoms consistent with FASD

McQuire et al., 2019

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Teratogens: Environmental Toxins

radiation (nuclear meltdowns, ordinary x-rays)
* miscarriage
* stunted growth
* physical defects
* cancer
pollution (lead, mercury)
* prematurity
* LBW
* cognitive delays

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Teratogens: Air pollution & brain development

why is it hard to establish casual links?

objective measure of brain development (e.g. use of self-report q’s, sample selection etc.)
what is precise exposure
most vulnerable ages particularly hard to study

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Teratogens: Air pollution & brain development

experiment in mice

in mice - structural brain abnormalities
direct action
- exposure to directly teratogenic substances
indirect action
- reduced O2 availability

Sunyer & Dadvand, 2018

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Teratogens: Infectious Disease

TORCH

Toxoplasmosis
Other virsus
Rubella
CMV
Herpes

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Toxoplasmosis

parasitic infection in cats & raw meat
* brain & eye damage

Other viruses

e.g. HIV & AIDS
* mortality, small head, physical & mental defects

Rubella

virsus damages eyes, ears, heart
* causes mental retardation

CMV

virus with mild (or no) flu-like symptoms

Herpes

sexually-transmitted virus
* damages eyes, brain, motor system

Teratogens: Infectious Diseases (2)

Zika Virus

mosquito-bourne infection, identified in Uganda -> 2016 epidemic: Asia, South America
* mild fever in mother
* casual link to infant microcephaly (small brain) confimed (2016)
* infects foetal brain tissue
* no vaccine (yet)
* lifelong sensory, motor & cognitive diability

Other Risks: Maternal Factors

age

age
* fertility problems increase w/ age
* miscarriage & chromosomal damage increases w/ age
* teen moms at risk

Other Risks: Maternal Factors

nutrition

weight gain
affected by ethnicity and SES
folic acid: neural tube defects
- Spina Bifida
- Aencephaly

Other Risks: Maternal Factors

prenatal care & health

toxemia/pre-eclampsia:
* pregancy-caused high blood pressure - restricted growth, preterm birth, stillbirth
* (gestational) diabetes - high birth weight, preterm birth, temporaty breathing problems

Perinatal complications: Prematurity | 36 weeks

preterm: < 36 wks * avg weight: 2.3 kg (5 lb) * risk of cognitive delay * appropriate weight for pregnancy length

Perinatal complications: Prematurity | 32 weeks & 26 weeks

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

Perinatal complications: Low Birth Weight

small-for-date * full-term or preterm * BELOW expected weight for pregancy length * normal birth weight is approx. 3.5 kg (7.7 lb)

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)

can LBW babies catch up?

yes, most catch up by 4 years but: * can have motor & cognitive problems longer term

Stimulation Programmes for Preterm Babies

* Used to be isolated to protect health * But under-stimulation delays development * mimics sensation of the womb

The Breathing Bear with Preterm Infants | who was the study run by?

Thomas et al., 1995

The Breathing Bear with Preterm Infants | what was investigated?

the sleep/wake states of preterm babies

The Breathing Bear with Preterm Infants | method

1. At 33 wks conceptual age (CA), babies were randomly assigned to a Breathing Bear (BB) or a Non-Breathing (NB) Bear condition 2. At 35 wks CA, behavioral observations were made over a 2-hr period, recording babies’ sleep/wake states: active sleep, quiet sleep, sleep-wake transition,waking, or fuss/crying. 3. movements and startles were also measured

The Breathing Bear with Preterm Infants | results

* BB bear 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

Massage Stimulates Growth in Preterm Infants | Field, 1990

Preterm infants were assigned to treatment and control groups. * Treatment infants received three 15-min massages daily for 10 days. * Control infants received no massage. * Treated infants gained more weight per day * Discharged from hospital several days earlier than control infants.

parent interventions | why are preterm babies likely to get less sensitive care?

preterm babies need even more sensitive care than full-term babies, but likely to get even less senstivie care due to: * physical appearance * high-pitched cry * feeding difficulties * lower responsiveness * hospital or home-based interventions aim to improve parent-infant interaction

parental interventions | effectiveness of interventions: what does it depend on (5 factors)

* **Nature of intervention** (e.g., massage, maternal sensitivity, infant self- regulation) * **Infant charecteristics** (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., atttion, behaviour problems)