Introduction
Women with polycystic ovary syndrome (PCOS) have increased risk of pregnancy complications, including preterm birth before 37 weeks. However, if this increased risk also includes extremely preterm births (<28 weeks) is unknown. Such information is important to identify women at risk and tailor antenatal care, since child morbidity and mortality become more prevalent with increasing prematurity.
Aims
To investigate the association between PCOS and extremely preterm birth, and whether onset of PCOS-related preterm birth is predominantly spontaneous or medically indicated.
Material and methods
This was a nationwide register-based cohort study in Sweden. The study population was all live singleton births registered in the Swedish Medical Birth Register 2005–2014 (n = 1 046 448). Women with and without PCOS were compared by severity of preterm birth [extremely (22+0 to 27+6 weeks), very (28+0 to 31+6 weeks) and moderately (32+0 to 36+6 weeks)] and delivery onset mode (spontaneous or medically indicated). Multinomial logistic regression was performed to estimate adjusted odds ratios (aOR) with 95% confidence intervals (CI). Adjustments were made for maternal age, parity, body mass index, smoking, country of birth and year of delivery.
Results
During the study period, 1.3% of the women giving birth had PCOS diagnosis. They had an overall higher preterm birth rate than women without PCOS (6.7% and 4.8%, respectively). Women with PCOS had increased odds of preterm birth of all severities, with the highest odds for extremely preterm birth (aOR 2.3; 95% CI 1.7–3.0), particularly of spontaneous onset (aOR 2.7; 95% CI 2.0–3.6).
Conclusions
Women with PCOS had more than a two-fold increased risk of extremely preterm birth with spontaneous onset than women without such diagnosis. This can be important in antenatal risk assessment of preterm birth in women with PCOS. Future research is warranted to investigate the biological mechanisms behind preterm birth in women with PCOS.
Objective
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.
Design
Nationwide register‐based cohort study.
Setting
Sweden.
Population
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.
Methods
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.
Main outcome measures
Stillbirth, at ≥22 weeks of gestation in 2008–2015 and at ≥28 weeks of gestation in 1997–2007.
Results
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.
Conclusions
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.
Tweetable abstract
Women with PCOS have increased risk of stillbirth, and the incidence is particularly increased at term.
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