Association of Maternal Hyperlipidemia Combined with Gestational Diabetes Mellitus with Adverse Maternal and Neonatal Outcomes: A Retrospective Cohort Study.

Background: Hyperlipidemia and gestational diabetes mellitus (GDM) are common metabolic disorders during pregnancy and have each been associated with adverse maternal and neonatal outcomes. However, evidence regarding the combined association of maternal hyperlipidemia and GDM with pregnancy outcomes remains limited. Objective: To evaluate the association between maternal hyperlipidemia combined with GDM and adverse pregnancy outcomes in a retrospective cohort of pregnant women with hyperlipidemia. Methods: This retrospective observational cohort study included 3,526 singleton pregnant women diagnosed with hyperlipidemia during late pregnancy. Participants were categorized into a non-GDM group (n=2,684) and a GDM group (n=842) according to the results of the oral glucose tolerance test performed at 24-28 weeks of gestation. Multivariable logistic regression analyses were conducted to assess the associations between hyperlipidemia combined with GDM and adverse pregnancy outcomes after adjustment for maternal age, gravidity, parity, gestational weight gain, pre-pregnancy body mass index (BMI), educational level, mode of conception, and mode of delivery. Results: Compared with women with hyperlipidemia alone, women with hyperlipidemia combined with GDM were more likely to experience preterm birth (PTB) at 34-36+6 weeks (adjusted odds ratio [aOR] 1.986, 95% confidence interval [CI] 1.384-2.849; P<0.001) and intrahepatic cholestasis of pregnancy (ICP) (aOR 1.716, 95% CI 1.184-2.489; P=0.004). Hyperlipidemia combined with GDM was also associated with increased odds of large for gestational age infants (LGA) (aOR 1.213, 95% CI 1.028-1.433; P=0.023), macrosomia (aOR 1.445, 95% CI 1.116-1.872; P=0.005), and admission to the general neonatal ward (aOR 1.229, 95% CI 1.017-1.487; P=0.033). In contrast, inverse associations were observed for oligohydramnios (aOR 0.410, 95% CI 0.206-0.816; P=0.011) and congenital anomalies (aOR 0.326, 95% CI 0.114-0.929, P=0.036). Sensitivity analyses demonstrated that the associations with PTB, ICP, LGA, and macrosomia remained robust after exclusion of pregnancies conceived through assisted reproductive technology. Conclusion: Among pregnant women with hyperlipidemia, coexisting GDM was associated with higher odds of PTB at 34-36+6 weeks, ICP, LGA, macrosomia, and neonatal ward admission. These findings may contribute to risk stratification among women with combined glucose-lipid metabolic abnormalities during pregnancy; however, prospective studies are required to confirm these associations.