Prenatal Development and Care
The three prenatal stages
- Germinal (zygote) stage: conception to about 2 weeks; rapid cell division and implantation.
- Embryonic stage: about 3 to 8 weeks; major organ systems form; most vulnerable to teratogens.
- Fetal stage: about 9 weeks to birth; growth and maturation of organs; movement felt, viability later.
Critical periods and teratogens
A teratogen is any agent that can disturb prenatal development. Examples include alcohol, tobacco, certain drugs, rubella, radiation and maternal infections. Effect depends on timing, dose and genotype. The embryonic period is the peak period for structural defects; later exposure tends to affect growth and function.
Care of the expectant mother
Balanced diet with adequate protein, iron, folate, calcium; regular antenatal checks; avoidance of alcohol, smoking and self-medication; management of anaemia, blood pressure and infections; rest and emotional support; institutional delivery and breastfeeding preparation.
Worked example
A mother has rubella at 6 weeks gestation versus 30 weeks. Reasoning: at 6 weeks the embryo is forming organs, so risk of structural defects in heart, eye and ear is high. At 30 weeks organs are formed, so risk shifts toward growth restriction, hearing damage or infection effects. Timing, not just the agent, drives the answer.
Traps
Zygote is not the embryo; the embryonic stage is not from 8 weeks to birth; alcohol is not harmless in small amounts; do not say all medicines are safe in pregnancy; do not confuse folate with iron.