ObjectiveThis study aimed to investigate the relationship between maternal serum uric acid levels in the first trimester and the incidence of congenital heart diseases (CHDs) in offspring. MethodsThis prospective cohort study was conducted in the southeast of China and involved 21,425 pregnant women and their offspring in the final analysis between 2019 and 2022. Fasting blood samples from pregnant women participating in the Fujian birth cohort study (11.3 ± 1.40 weeks of gestation) were analyzed for serum uric acid levels. The perinatal outcome was the incidence of CHDs. All fetuses with CHDs were confirmed by echocardiography doctors and pediatric cardiologists. Logistic regression analysis and restricted cubic spline (RCS) modeling were employed to investigate the relationship between serum uric acid level and the incidence of CHDs. ResultsWe observed that maternal log2-transformed values of serum uric acid were strongly associated with odds of CHDs in offspring (adjusted odds ratio [AOR] 1.589, 95 % CI [1.149, 2.198]). Compared to the lowest quartile, the AORs for maternal uric acid levels in the other quartiles and the corresponding risk of CHDs in offspring were 1.363 (95 % CI [1.036, 1.793]), 1.213 (95 % CI [0.914, 1.610]), and 1.472 (95 % CI [1.112, 1.949]), respectively. Hyperuricemia in the first trimester significantly increased the risk of CHDs in offspring 1.837 (95 % CI [1.073, 3.145]). Furthermore, RCS showed a linear relationship between maternal serum uric acid levels in the first trimester and the incidence of CHDs (P for nonlinearity = 0.71). ConclusionsThe results of this study indicated that elevated maternal serum uric acid levels in the first trimester were associated with an increased incidence of CHDs in offspring.