Polycystic ovary syndrome and risk of stillbirth: a nationwide register-based study

To investigate whether polycystic ovary syndrome (PCOS) is associated with increased risk of stillbirth and whether any such association is linked to PCOS with a severe hyperandrogenic profile.

Nationwide register-based cohort study.

Sweden.

The cohort consisted of women giving birth to singleton infants in 1997-2015. All women with a diagnosis of PCOS in the period 1997-2017 and a randomly selected reference group of women without PCOS diagnosis were included. PCOS with a severe hyperandrogenic profile was defined as a PCOS diagnosis with at least two dispensations of prescribed anti-androgens during 2005-2017.

The risk of stillbirth in women with PCOS was estimated through multiple logistic regression, using women without PCOS as a reference. Risks were expressed as adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs), adjusted for maternal age, parity, body mass index, type-1 diabetes, educational level and country of birth.

Stillbirth, at ≥22 weeks of gestation in 2008-2015 and at ≥28 weeks of gestation in 1997-2007.

Compared with women without PCOS (n = 241 750), women with PCOS (n = 41 851) had a 50% increased risk of stillbirth (aOR 1.50, 95% CI 1.28-1.77). The incidence of stillbirth in women with PCOS was particularly increased at term. Women with PCOS and a severe hyperandrogenic profile (n = 13 713) did not have a stronger association with stillbirth than women with PCOS who did not have such a profile.

PCOS is associated with stillbirth and should be considered as a possible risk factor in antenatal care. Further research is warranted to investigate possible causal mechanisms.

Women with PCOS have increased risk of stillbirth, and the incidence is particularly increased at term.