Women with polycystic ovary syndrome (PCOS) are more likely to suffer adverse pregnancy and birth outcomes, a population-based cohort study from Sweden suggests. The researchers identified women with singleton pregnancies who gave birth between 1995 and 2007, using the Swedish medical birth register. Using linkage to another national database, they established that, in this cohort, 3,787 births were to women with diagnosed PCOS and 1,191,336 were to women without the disease. Data on maternal and fetal pregnancy outcomes were collected. Comments Dr Chris Barclay: 'We know that women with PCOS are more likely to be overweight and are at greater future risk of diabetes and cardiovascular disease. The results of this study suggest that they are also more likely to have high-risk pregnancies. There are two observations I would like to make on this study. First, the numbers of women with diagnosed PCOS here were small, and this may have obscured the magnitude of its adverse effects on pregnancy. Second, nowhere in the paper were the significance of hyperinsulinism or the metabolic syndrome discussed which considering they are common and relevant characteristics of PCOS was baffling.'