Obesity, as defined by body mass index (BMI) is one of the biggest challenges facing health care system including maternity services today, particularly in the industrialized nations. Maternal obesity is linked with a number of pregnancy complications including gestational diabetes, preeclampsia, venous thromboembolism, caesarean delivery, postpartum haemorrhage, macrosomia, shoulder dystocia and poor perinatal outcomes. Obesity has also been shown to be independently associated with higher odds of dying from specific pregnancy complications. These risks increases with increasing BMI and are highest in women with BMI ≥ 50. The mechanisms underlying these pathologies remain unclear. All obese women in reproductive age group should be counselled about weight gain, exercise programmes, nutrition and food choices, longer term health risks and increased risk of maternal and fetal complications, ideally before contemplating pregnancy. They should also be supported to lose weight and optimise their health before conception. Obese pregnant women should receive routine care supplemented by specialist services and facilities that are specific to their needs, to improve maternal and perinatal outcomes.