Excessive bile acids level predisposes to adverse perinatal outcomes in women with abnormal pre-pregnancy body mass index

Both low/high pre-pregnancy body mass index (BMI) and increased bile acid levels during pregnancy (known as gestational hypercholanemia) were risk factors for adverse pregnancy outcomes, with limited information on their joint effects. A total of 63,066 pregnant women were involved in a large retrospective cohort study from May 2014 to December 2018 in Shanghai, China. Data of pregnancy outcomes including hypercholanemia, hypertensive disorders in pregnancy (HDP), preterm delivery, and small for gestation age (SGA), were obtained for multivariable logistic analysis. Pre-pregnancy BMI was negatively associated with serum total bile acid (TBA) concentrations during gestation and the risk of hypercholanemia (<i>p</i> &lt; 0.001). Low pre-pregnancy BMI and hypercholanemia coexisting were related to a 2.71-fold risk (95% confidence intervals [CI], 2.10-3.50) of SGA. Whereas, overweight/obese (OWO) with hypercholanemia are associated with 5.34-fold risk (95% CI 3.93-7.25) of HDP when compared with normal weight women without hypercholanemia. Women with excessive gestational weight gain (GWG) and hypercholanemia had a higher risk of HDP (odds ratio [OR] 3.56, 95% CI 2.91-4.36), and macrosomia (OR 2.95, 95% CI 2.42-3.60), compared with non-hypercholanemia women with adequate GWG. Whereas, women with inadequate GWG and hypercholanemia had increased risks of preterm delivery (OR 1.87, 95% CI 1.44-2.43), and SGA (OR 2.32, 95% CI 1.82-2.96). Low maternal BMI before pregnancy was an independent risk factor for hypercholanemia. Additionally, pre-pregnancy underweight or OWO may amplify the effect of hypercholanemia on adverse pregnancy outcomes. Thus, pre-pregnancy BMI should be considered in the management of adverse perinatal outcomes related to gestational hypercholanemia. Low maternal BMI before pregnancy was a risk factor for gestational hypercholanemia. Pre-pregnancy overweight mothers with hypercholanemia had a higher risk of hypertensive disorders of pregnancy, while underweight mothers with hypercholanemia had a higher risk of delivering small for gestational age infants. These findings emphasize the importance of considering pre-pregnancy BMI as a stratification factor in the management of adverse maternal and neonatal outcomes related to hypercholanemia.