prenatal development and birth Flashcards
(15 cards)
What are the 3 stages of prenatal development and outline them
Zygote/germinal stage 0-2 weeks: conception to implantation
Embryo 3-8 weeks:
- Neural tube becomes brain and spinal cord
- Amniotic sac: the fluid filled membrane protecting the embryo
- Placenta: disc-like structure connecting embryo to uterus
- Umbilical cord: tube connecting embryo to placenta, provides oxygen and nutrients and removed carbon dioxide and waste
- Miscarriage risk highest at this point.
Foetus stage 9-38 weeks:
- Brain and CNS development, the connections strengthen and cerebral cortex develops a lot
- 12 weeks: can tell sex and reflexes develop
- 17-20 weeks: mother feels movement and feel touch reflexes
- 22-26 weeks: viability, if the baby is born prematurely it could survive
What is a teratogen
An environmental agent that causes prenatal damage
Effects can occur during critical/sensitive periods.
- Effects are specific and longer exposure is worse
Some have no effect on mother and maternal/foetal genes may counteract effects
What is Thalidomide and DES
Thalidomide:
Is a prescription drug used for morning sickness (1957-61) and caused structural abnormalities in limbs and face and then withdrawn in 1961.
DES:
Hormone used to prevent miscarriage, linked to reproductive problems and cancers in offsprings
What are some legal teratogens or legal substances
Caffeine (can lead to miscarriage, low birthweight)
Tobacco (chemicals in smoke can lead to miscarriage and prematurity)
- Nicotine affects placenta, leading to poor nutrition and low birth weight
- Can lead to ADHD
- Roza et al 2007:affects head circumference
Alcohol: passes right through placenta into foetus
- Foetal Alcohol Syndrome: stunted growth, physical changes, often mental retardation.
- Last trimester worst (unlinke most teratogens, affects brain development as this is period of time where it is developing rather than structure)
What are some environmental toxins
Radiation (atomic bombs, nuclear reactor meltdowns, X-rays) can lead to Miscarriages, stunted growth, physical defects, cancer.
Pollution (lead, mercury like in tuna PCBS) lead to prematurity, low birth weight or cognitive impairments.
Air pollution particles found in mothers placenta
Infectious TORCH diseases
Toxoplasmosis: parasitic infection in cats and raw meat- eye and brain damage
Other viruses: AIDS/HIV- small head and other mental+ physical defects
Rubella: Virus damages eyes, ears, heart and causes mental retardation
CMV: Virus with mild or no flu-like symptoms
Herpes: sexually-transmitted virus- damages eyes, brain and motor systems
Zika Virus: mosquito-borne infection- cause mild fever in mother and link to microcephaly (small brain), infecting foetal brain tissue, leading to life longs sensory, motor and cognitive disability (not TORCH)
Other maternal risk factors that can affect development
1) Age
- Fertility problems increase with age
- Miscarriage and chromosomal damage risks increase with age
- Teen mothers also at risk and are less likely to heave prenatal care
- Older mothers who have had a child have a lower risk of defects
2) Nutrition:
- Weight gain
- Affected by ethnicity and SES
- Can impact neural tube and if it doesn’t close at the end, there will not be enough Folic acid, leading to Anencephaly (absence of part of the skull and deformed cerebral cortex)
- If is does not close at the lower end, the spinal cord sticks out
3) Prenatal care
- Health
- Toxaemia/Pre-eclampsia: pregnancy-caused high blood pressure leading to restricted growth, preterm birth, still birth
4) Diabetes
- High birth weight, preterm birth, temporary breathing problems.
What is the APGAR scoring system
Activity
Pulse
Grimace (reflex irritability)
Appearance (skin colour and reparations)
One minute and then 5 minutes after the baby is born
10 is perfect condition
What are the risks with preterm babies
Pre-term is before 36 weeks and is less than ten percent of UK births. Risk of cognitive delay and babies are 2.3kg on average which is the appropriate weight for pregnancy length.
Extremely preterm is before 26 weeks:
- May cause respiratory distress syndrome
- Inadequate surfactant (liquid in lungs that sends o2 into blood)
- Hard to predict what causes preterm births
What are the risks with small for date babies (LBW)
Full term or pre term: below expected weight for pregnancy length
Normal birth weight is approximately 3.5kg
LBW is less than 2.5kg and Very LBW is less than 1.5 and extremely LBW under 1 kg.
Can lead to uses with placenta and consequently infections
Links with learning and mental difficulties, poor social skills and issues in school
However most catch up by 4 years.
Babies less than 1.5kg make less friends and reach lower qualifications through rating self-esteem and quality of life compared to peers - Babies born 1986
Why are stimulation programmes used for babies
Used to be isolated to protect health but now we know under stimulation delays development.
Stimulation tires to mimic the sensations of the womb.
Skin to skin contact (kangaroo care) used to keep their temperature regulated as if they were inside the womb
Using massages
Do we interact as if they are newborns or is this over stimulating?
3 types of stimulation programme are: breathing bear, massage stimulation and parent intervention
Breathing bear
e.g. Thoman et al 1995 as in Leman et al 2012:
- Investigate the sleep/wake stages of preterm babies
- At 33 wks, conceptional age babies were randomly assigned to a breathing bare or non breathing bear condition.
○ At 35 weeks conceptional age, behavioural observations were made over a 2 hour period, recording babies sleep wake states: Active sleep, quiet sleep, sleep- wake transition, waking or fuss/crying
○ As well as movements and startles
- BB babies showed less waking and more quiet sleep, less startles and crying in quiet sleep and were more likely to smile than grimace during active sleep.
- No difference in respiration rates between groups
Original purpose was to see difference in respiration rates
Massage stimulation
Preterm infants assigned to treatment and control groups
Treatment infants received three 15min massages daily for 10 days and control infants received none.
Treated infants gained more wight per day and were discharged several days earlies
Parent interventions:
Parent interventions
Pre term babies need even more sensitive care than full term but are less likely to get it due to
- Physical appearance: babies look smaller and different which may distress parent
- High-pitched cry which can set parents on edge
- Feeding difficulties
- Lower responsiveness may cause parent distress
Hospital or home based interventions were used
Effectiveness depends on many factors ( Landsem et al 2015; Welch et al 2015)
- Nature of interventions (is it a massage, maternal sensitivity, infant self-regulation)
- Infant characteristics (how preterm, how stable/ healthy)
- Intervention duration (short term interventions may only have short term effects )
- Length of follow up ( 6 months or 9 years?)
- Outcome measures (physical development, cogitive development, attention, behaviour problems- might be more effective for different problems
