ObstetricsTier 2Topic

Optimising the management of pre-existing medical conditions prior to conception

Overview

Pre-conception review and optimisation of chronic medical conditions to minimise maternal and fetal risk before pregnancy is attempted
Applies most critically to diabetes, epilepsy, hypertension, thyroid disease, psychiatric illness, and anticoagulation

Unplanned pregnancy is common - many women with chronic disease conceive without pre-conception optimisation, missing the highest-yield window

Diabetes - periconceptional hyperglycaemia is directly teratogenic; risk of congenital malformation (cardiac, neural tube) rises with HbA1c - target HbA1c <=6.5-7% (48-53mmol/mol) before conceiving
Epilepsy - valproate is highly teratogenic and contraindicated in women of childbearing potential without exceptional circumstances; switch to lower-risk agents (lamotrigine, levetiracetam) pre-conception where possible; use folic acid 5mg (higher dose)
Hypertension - stop ACEi/ARB (teratogenic), switch to pregnancy-safe agents (labetalol, methyldopa, nifedipine)
Anticoagulation - warfarin is teratogenic (embryopathy in the first trimester) - switch to heparin/LMWH before, or as soon as pregnancy is confirmed if mechanical valve/high thrombotic risk

Structured pre-conception visit: medication review, disease control assessment (HbA1c, seizure frequency, BP), immunisation update (rubella, varicella status), folic acid/iodine initiation, genetic counselling if relevant

Individualised by condition (see aetiopathogenesis); involve the relevant specialist (endocrinologist, neurologist, cardiologist) alongside the obstetric team
Continue contraception until disease control and medication changes are confirmed safe before attempting conception

Congenital malformation rates correlate directly with the degree of pre-conception disease control across diabetes, epilepsy, and maternal PKU

The critical teratogenic window (organogenesis) is weeks 3-8 post-conception, often before pregnancy is recognised - this is why optimisation must happen before, not after, a positive test

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