Independently increases the risk of adverse pregnancy and birth outcomes Polycystic ovary syndrome is a common condition. The reported incidence varies between 3% and 15% of women of reproductive age, depending on the population studied and the diagnostic criteria applied,1 which include hyperandrogenism, anovulation, and polycystic ovaries. Rising obesity rates are likely to increase the incidence further. The implications of this for those who care for women in pregnancy are highlighted in the linked cohort study, in which Roos and colleagues assess the risk of adverse pregnancy outcomes in women with a diagnosis of polycystic ovary syndrome, taking maternal characteristics and assisted reproductive technology into account (doi:10.1136/bmj.d6309).2 Although polycystic ovary syndrome is associated with increased long term risks of type 2 diabetes and cardiovascular disease, most affected women present initially with anovulatory infertility. Weight loss can resolve this, but it is often difficult to achieve and medical treatments are usually required. Most will respond to anti-oestrogen treatment, and those who do not usually ovulate when given exogenous gonadotrophins.3 However, in vitro fertilisation is being …