Obesity is increasing; in the UK, almost 20% of pregnant women have a body mass index (BMI) of ≥30 kg/m(2). Obese mothers have increased risks of pregnancy complications including miscarriage, congenital anomaly, gestational diabetes, pre-eclampsia, macrosomia, induction of labour, caesarean section, anaesthetic and surgical complications, post-partum haemorrhage, infection and venous thromboembolism. Complications tend to be greater in those with the highest BMIs. In recent triennia, obesity (27-29%) was over-represented in maternal mortality figures. Strategies to reduce morbidity and mortality include calculating BMI at booking visit to identify obese mothers and plan their antenatal care and delivery. This should include nutritional and lifestyle advice, screening for gestational diabetes and pre-eclampsia, thromboembolism risk assessment, antenatal anaesthetic review if BMI is ≥ 40 kg/m(2), ensuring availability of robust theatre tables and other equipment and involving senior doctors, especially in the labour ward. Afterwards, continuing weight reduction should be encouraged to reduce future pregnancy and health risks.