Obesity and pregnancy

Overview

•BMI ≥30 → consultant-led care

•BMI ≥40 → refer to obstetric anaesthetist antenatally (epidural technically more challenging)

•NHS-funded IVF → BMI must be 19-25 for at least 6 months prior to referral

Management

•Pre-conception: advise weight loss before conception; refer to structured weight management programme

•Folic acid: folic acid 5mg daily from 1 month before conception to 13 weeks (higher dose due to impaired folate metabolism in obesity; standard dose is 400 micrograms)

🎯

Obese women require folic acid 5mg daily - not the standard 400 micrograms. This is a high-yield pre-conception point.

•Pre-eclampsia prophylaxis: aspirin 75mg daily from 12 weeks if additional risk factors present (age ≥40, pre-existing hypertension, previous pre-eclampsia)

•Gestational diabetes screening: OGTT at 24-28 weeks

•VTE prophylaxis (antenatal): enoxaparin (LMWH) - safe in pregnancy as it does not cross the placenta

•VTE prophylaxis (postnatal): enoxaparin minimum 10 days; up to 6 weeks if BMI ≥40, emergency caesarean, or additional risk factors

•Monitoring: BP and urine dipstick at every antenatal appointment; serial growth scans for macrosomia

•Delivery: consultant-led obstetric unit only

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Postnatal LMWH duration is risk-stratified - not a flat 10 days. Women with BMI ≥40 or emergency caesarean section may need enoxaparin for up to 6 weeks postpartum.

Complications

Maternal and foetal complications

Gestational diabetes

Pre-eclampsia (2-4x higher risk)

Venous thromboembolism

Operative delivery (forceps, ventouse, emergency CS)

Macrosomia

Neural tube defects (impaired folate metabolism)