For obese women the risks of adverse outcomes during pregnancy, for both the mother and her child, are significantly higher than for the general population. In 2016, 21% of all women attending antenatal services in the UK were reported to have a BMI of 30 kg/m² or higher. In 2003-2005, 27% of all maternal deaths occurred in women with a BMI of 30 kg/m² or higher. Obesity increases the risk of venous thromboembolism, gestational diabetes, pre-eclampsia and hypertension. There is an increased likelihood of induction of labour, instrumental delivery and postpartum haemorrhage. The greatest effect on risk reduction is weight loss prior to conception.