Obesity in women of reproductive age is increasing in prevelance worldwide. Obesity reduces fertility and increases time taken to conceive, and obesity-related comorbidities (such as type 2 diabetes and chronic hypertension) heighten the risk of adverse outcomes for mother and child if the woman becomes pregnant. Pregnant women who are obese are more likely to have early pregnancy loss, and have increased risk of congenital fetal malformations, delivery of large for gestational age infants, shoulder dystocia, spontaneous and medically indicated premature birth, and stillbirth. Late pregnancy complications include gestational diabetes and pre-eclampsia, both of which are associated with long-term morbidities post partum. Women with obesity can also experience difficulties during labour and delivery, and are more at risk of post-partum haemorrhage. Long-term health risks are associated with weight retention after delivery, and inherent complications for the next pregnancy. The wellbeing of the next generation is also compromised. All these health issues could be avoided by prevention of obesity among women of reproductive age, which should be viewed as a global public health priority. For women who are already obese, renewed efforts should be made towards improved management during pregnancy, especially of blood glucose, and increased attention to post-partum weight management. Effective interventions, tailored to ethnicity and culture, are needed at each of these stages to improve the health of women and their children in the context of the global obesity epidemic.