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.

Women with PCOS were more likely to have used assisted conception treatment (13.7% vs 1.5%, p < 0.001) and be obese (60.6% vs 34.8%, p < 0.001) compared with women who did not have the condition. They were also more likely to have pre-existing diabetes or hypertension.

After controlling for variables (which included age, BMI, and use of assisted conception techniques) women with PCOS were more likely to develop gestational diabetes, RR 2.32 (95% CI: 1.88-2.88, p < 0.001) and pre-eclampsia, RR 1.45 (95% CI: 1.24-1.69, p < 0.001), and require Caesarean section, RR 1.18 (95% CI: 1.07-1.29, p = 0.001). They were also more likely to have a very preterm birth (

Babies of mothers with PCOS were no more likely to be stillborn but they were significantly more likely to be macrosomic, RR 1.16 (95% CI: 0.99-1.36, p = 0.072) and distressed at birth i.e. have lower Apgar scores, RR 1.41 (95% CI: 1.09-1.83, p = 0.0095) and meconium aspiration, RR 2.02 (95% CI: 1.13-3.61, p = 0.018).

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.

Dr Chris Barclay

• Roos N, Kieler H, Sahlin L et al. Risk of adverse pregnancy outcomes in women with polycystic ovary syndrome: population based cohort study. BMJ 2011;343:d6309