A decade of nationwide data from China suggests that polycystic ovary syndrome is becoming increasingly visible in pregnancy, while also highlighting a substantial rise in maternal and fetal complications among affected women. The large observational study, based on nearly 14.1 million pregnancies, found that the recorded prevalence of polycystic ovary syndrome, or PCOS, increased from 0.79 cases per 10,000 pregnancies in 2012 to 19.0 per 10,000 in 2021. Researchers from West China Second University Hospital and Sichuan University say the findings underscore the need for earlier diagnosis, closer antenatal monitoring and more individualized obstetric care, particularly as China’s reproductive landscape has changed dramatically over the past decade.
PCOS is one of the most common endocrine disorders affecting women of reproductive age, with global estimates ranging from approximately 6% to 20%. The condition is characterized by hormonal and metabolic disturbances that can include irregular ovulation, elevated androgen levels and polycystic ovarian morphology. Insulin resistance, obesity and chronic low-grade inflammation frequently accompany the syndrome, although the clinical presentation varies widely. Because symptoms can be subtle or attributed to normal reproductive variation, many women remain undiagnosed until they encounter difficulties with conception or complications during pregnancy. Pregnancy itself can amplify the metabolic and vascular challenges associated with PCOS, creating a complex clinical environment for both mother and fetus.
The study analyzed records collected between 2012 and 2021 by the Chinese Maternal Near Miss Surveillance System. The dataset included pregnancies managed in 438 hospitals distributed across 30 provinces, with representation from urban and rural communities and from eastern, central and western regions of mainland China. This broad geographic coverage gave the investigators an opportunity to examine national trends rather than relying on data from a single hospital or region. The researchers used interrupted-time-series analysis to evaluate changes around the introduction of China’s Universal Two-Child Policy, which took effect in 2016, and applied Poisson regression to estimate the relative risks of adverse outcomes associated with PCOS.
The statistical pattern indicated that the PCOS rate had already been increasing modestly before the policy took effect. During the period before June 2016, the estimated trend coefficient was 0.041, with a P value of 0.02. After the policy became effective, the increase was considerably steeper, with a coefficient of 0.227 and a P value below 0.001. The analysis cannot establish that the policy itself caused the increase, since changes in diagnostic practices, referral patterns, health awareness, reproductive behavior and hospital reporting may also have contributed. Nevertheless, the timing of the sharper rise suggests that the policy period coincided with a major shift in the profile of pregnant women being treated in China’s healthcare system.
The Universal Two-Child Policy was associated with a growing proportion of pregnancies among women of advanced maternal age. It also coincided with greater use of assisted reproductive technologies and an increase in multiple pregnancies, factors that can independently raise the likelihood of obstetric complications. These demographic and clinical changes may have influenced how PCOS was detected and recorded. Women who become pregnant at older ages or through fertility treatment are more likely to undergo intensive medical evaluation, potentially increasing the identification of previously unrecognized PCOS. At the same time, the metabolic and vascular demands of pregnancy may be greater in women with underlying insulin resistance or ovulatory dysfunction, making systematic screening and risk assessment especially important.
Among the pregnancies included in the analysis, PCOS was associated with substantially higher risks of several maternal complications. The adjusted relative risk of diabetes was 2.10, with a 95% confidence interval of 1.95 to 2.26, meaning that women with PCOS experienced approximately twice the risk observed among women without the condition after statistical adjustment. The risk of gestational hypertension was 2.37, while preeclampsia had a relative risk of 2.29. Superimposed preeclampsia, which develops in a woman who already has chronic hypertension, showed an even stronger association, with an adjusted relative risk of 5.28. HELLP syndrome, a severe pregnancy complication involving hemolysis, elevated liver enzymes and low platelet counts, was also more common, with an adjusted relative risk of 1.84.
The study further linked PCOS with a higher likelihood of cesarean delivery. The adjusted relative risk was 1.32, indicating a 32% higher risk compared with pregnancies without PCOS after accounting for measured factors. Some of this increase may reflect the greater frequency of hypertension, diabetes, fetal growth abnormalities or labor complications in this population. However, the investigators emphasize that PCOS should not be viewed as a single uniform risk state. The condition interacts with age, parity, access to antenatal care, pre-existing metabolic disease and the number of fetuses. These factors can combine to produce very different risk profiles, making broad recommendations less useful than targeted surveillance based on individual clinical characteristics.
Fetal and neonatal outcomes were also adversely affected. Pregnancies in women with PCOS had an adjusted relative risk of 1.66 for abortion and 1.81 for preterm birth. The risk of delivering a full-term infant with low birth weight was 1.38, while macrosomia, or excessive fetal growth, had a relative risk of 1.37. These apparently contrasting outcomes reflect the diverse biological pathways involved. Insulin resistance and maternal hyperglycemia can promote excessive fetal growth, whereas placental dysfunction, hypertensive disease and other pregnancy complications can restrict growth or trigger early delivery. Neonatal asphyxia was also more frequent, with an adjusted relative risk of 1.72, indicating the importance of careful fetal assessment and preparedness for neonatal resuscitation when complications arise.
Subgroup analyses identified advanced maternal age, inadequate antenatal care, nulliparity and multiple pregnancy as particularly important risk factors among women with PCOS. The findings suggest that clinicians should assess metabolic health before or early in pregnancy, including glucose regulation, blood pressure and weight-related risk, while also monitoring fetal growth and placental function. Adequate antenatal visits may allow earlier detection of gestational diabetes, hypertension and preeclampsia, conditions that can progress rapidly if not recognized. For women carrying twins or higher-order multiples, the physiological burden is greater and the threshold for specialist referral may need to be lower. The researchers argue that these measures are especially relevant in health systems adapting to later pregnancies and more frequent use of assisted reproduction.
The authors describe the work as the first large national analysis to examine both PCOS trends and maternal-fetal outcomes across this period of changing fertility policy in mainland China. The rising recorded prevalence may partly reflect a genuine increase, but it may also indicate improved recognition of a condition that has historically been underdiagnosed. The study’s observational design means that residual confounding, variations in hospital reporting and changes in diagnostic criteria cannot be excluded. Even so, the scale of the dataset provides a powerful signal: pregnancy in the presence of PCOS deserves proactive, risk-based management rather than routine care alone. As reproductive patterns continue to evolve, integrating endocrine assessment with obstetric surveillance could help reduce preventable complications for mothers and newborns.
Subject of Research: People
Article Title: Prevalence, trends, and maternal–fetal outcomes in pregnant women with polycystic ovary syndrome in Chinese mainland
News Publication Date: 25-Jun-2026
Web References: https://doi.org/10.1097/CM9.0000000000004132
References: Chinese Medical Journal. “Prevalence, trends, and maternal–fetal outcomes in pregnant women with polycystic ovary syndrome in Chinese mainland.” DOI: 10.1097/CM9.0000000000004132.
Image Credits: Chinese Medical Journal
Keywords: polycystic ovary syndrome, PCOS, pregnancy, maternal health, fetal outcomes, preeclampsia, gestational diabetes, China, Universal Two-Child Policy, obstetrics
