ObjectiveTo investigate whether early-pregnancy insulin resistance in women with polycystic ovary syndrome (PCOS) is associated with adverse maternal pregnancy complications and neonatal/perinatal outcomes after adjustment for common metabolic confounders.MethodsThis retrospective cohort study included 168 pregnant women diagnosed with PCOS who were consecutively enrolled at Tongren Hospital from July 2023 to December 2024. Of these, 52 patients with insulin resistance (homeostasis model assessment of insulin resistance ≥ 2.77) were assigned to the PCOS with insulin resistance group, whereas 116 patients without insulin resistance were assigned to the PCOS without insulin resistance group. Multivariable binary logistic regression was performed to estimate adjusted associations between insulin resistance and gestational diabetes mellitus, adjusting for age, body mass index, family history of diabetes, and conception mode.ResultsBody mass index was significantly higher in the PCOS with insulin resistance group (p = 0.02). No significant differences were found in thyroid function indices or blood lipid levels across trimesters, neonatal birth weight, or perinatal outcomes (all p > 0.05). The incidence of gestational diabetes mellitus was higher in the PCOS with insulin resistance group than in the PCOS without insulin resistance group (30.77% vs. 17.24%, p = 0.04). After adjustment for potential confounders, insulin resistance (adjusted odds ratio = 2.09, 95% confidence interval: 1.02-4.28, p = 0.044) and higher body mass index (odds ratio = 1.19 per kg/m2, p = 0.038) remained independently associated with increased odds of gestational diabetes mellitus. No significant differences were observed in gestational hypertension, polyhydramnios, or premature rupture of membranes.ConclusionsIn this observational cohort, early-pregnancy insulin resistance was associated with a higher incidence of gestational diabetes mellitus after adjustment for body mass index and other confounders. These findings do not establish a causal relationship. Early standardized screening and targeted metabolic management of insulin resistance may help reduce gestational diabetes mellitus incidence; however, prospective studies are warranted to confirm this association.