Background: Polyendocrine ovarian metabolic syndrome (PMOS) is associated with metabolic, reproductive and pregnancy-related complications. However, the extent to which adverse pregnancy outcomes are influenced by maternal adiposity remains uncertain. We compared maternal and neonatal outcomes between women with lean and non-lean PMOS.

Methods: This study included 216 pregnancies affected by PMOS. Lean PMOS was defined as a body mass index (BMI) <25 kg/m², and non-lean PMOS as a BMI ≥25 kg/m². Pregnancy complications, neonatal anthropometry and Apgar scores were compared between groups. Regression models were adjusted for gestational age at booking, infant sex and ethnicity. Results are presented as adjusted odds ratios (aORs) or adjusted mean differences with 95% confidence intervals.

Results: Seventy-five women had lean PMOS and 141 had non-lean PMOS. Mean BMI was 22.09 and 30.96 kg/m², respectively (p<0.001), while maternal age, ethnicity and gestational age at booking were similar. Gestational diabetes was more common in non-lean than lean PMOS (13.0% versus 2.8%; p=0.017). After adjustment, non-lean PMOS was associated with substantially higher odds of gestational diabetes (aOR 5.26, 95% CI 1.17–23.70; p=0.031). Pre-eclampsia occurred in 8.0% of the non-lean group and in none of the lean group (p=0.017). Gestational hypertension was numerically more frequent in non-lean PMOS but was not statistically significant after adjustment (aOR 1.89, 95% CI 0.76–4.73; p=0.172). Birth weight was higher in non-lean PMOS in unadjusted analysis, but not after adjustment (mean difference 99 g, 95% CI −84 to 283; p=0.286). Other neonatal anthropometric measures and Apgar scores were similar.

Conclusion: Non-lean PMOS was strongly associated with gestational diabetes, whereas adjusted neonatal outcomes were comparable. Maternal adiposity may identify a higher-risk PMOS phenotype requiring early metabolic assessment, targeted gestational diabetes surveillance and preventive antenatal strategies.