Polycystic ovary syndrome as an independent risk factor for gestational diabetes and hypertensive disorders of pregnancy: a population-based study on 9.1 million pregnancies

STUDY QUESTION Does polycystic ovary syndrome (PCOS) confer an independent risk for the development of gestational diabetes mellitus (GDM), gestational hypertension (GHTN) and preeclampsia (PEC) based on analysis of the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (HCUP-NIS) database. SUMMARY ANSWER After controlling for all potential confounding effects, women with PCOS are at a 2-fold higher risk of developing GDM, a 50% increased risk for the development of GHTN and a 30% increased risk of developing PEC than women without PCOS. WHAT IS KNOWN ALREADY Currently, there is evidence of an increased prevalence of maternal pregnancy complications in women with PCOS. However, there remain significant gaps in understanding how PCOS affects the development of GDM, GHTN and PEC. This is most likely due to the complex, multifactorial etiology of PCOS, its range of potential confounders for pregnancy complications and the variable methodology of studies that have been conducted. To date, the largest meta-analysis on this subject includes 11 565 women with PCOS analyzed for their risk of GDM and 5896 patients analyzed for their risk of PEC. STUDY DESIGN, SIZE, DURATION This is a retrospective population-based study utilizing data from the HCUP-NIS over 11 years from 2004 to 2014. A dataset of all deliveries between 2004 and 2014 inclusively was created. Within this group, all deliveries to women with PCOS were identified as part of the study group (n = 14 882), and the remaining deliveries were categorized as non-PCOS births and comprised the reference group (n = 9 081 906). PARTICIPANTS/MATERIALS, SETTING, METHODS The HCUP-NIS is the largest inpatient sample database in the USA and is comprised of hospital inpatient stays submitted by hospitals throughout the entire country. Each year, the database provides information relating to 7 million inpatient stays, including patient characteristics, diagnosis and procedures. The data are representative of ∼20% of admissions to US hospitals across 48 states and the District of Columbia. MAIN RESULTS AND THE ROLE OF CHANCE At baseline, more pregnant women with PCOS were obese (22.3% vs. 3.5%, P < 0.001), had chronic hypertension (HTN) (8.4% vs. 1.8%, P < 0.001), had pregestational diabetes (4.1% vs. 0.9%, P < 0.001) and had treated thyroid disease (12.6% vs. 2.4%, P < 0.001). Women with PCOS were also more likely to have undergone IVF treatment (2.4% vs. 0.1%, P < 0.001), have multi-gestation pregnancies (5.9% vs. 1.5%, P < 0.001), and more multiple gestations (MGs) in the PCOS group were the result of IVF treatment than the non-PCOS groups (12.3% vs. 2.3%, P < 0.001). In all pregnancies, women with PCOS were more likely to develop gestational diabetes (adjusted odds ratio (aOR) 2.19, 95% CI 2.02–2.37), pregnancy associated HTN (aOR 1.38, 95% CI 1.27–1.50, P < 0.001), GHTN (aOR 1.47, 95% CI 1.31–1.64), PEC (aOR 1.29, 95% CI 1.14–1.45) and superimposed PEC (aOR 1.29, 95% CI 1.04–1.59) after controlling for confounding effects (age, race, income level, insurance type, obesity, IVF use, previous cesarean section, chronic HTN, pregestational diabetes, thyroid disease, MG, smoking and recreational drug use). Odds ratios were comparable between all pregnancies and singleton pregnancies only. In women pregnant with multiple fetuses, PCOS only conferred a statistically significant increased risk of developing GDM (aOR 2.33, 95% CI 1.92–2.83, P < 0.001). However, there was a trend toward an increased risk for developing pregnancy associated HTN (aOR 1.92, 95% CI 0.99–1.42, P = 0.058). LIMITATIONS, REASONS FOR CAUTION This is a retrospective analysis utilizing an administrative database which relies on the accuracy and consistency of the individuals coding the data. There are known limitations in how accurately hospital coding is able to capture perinatal conditions and complications, making it difficult to know with certainty that such events are accurate. WIDER IMPLICATIONS OF THE FINDINGS Pregnant women with PCOS are at increased risk of adverse complications in pregnancy even when they do not present with other coexisting metabolic conditions. Furthermore, it is important to also consider the risk of all other coexisting metabolic conditions frequently encountered in PCOS women, as these risks are additive and place women with PCOS at significantly increased risk for adverse complications in pregnancy. STUDY FUNDING/COMPETING INTEREST(S) None.