To investigate the associations between serum uric acid levels during the third trimester of pregnancy and risks of adverse pregnancy outcomes. In this retrospective study, a cohort of 7 995 pregnant women who were hospitalized for childbirth from January 2014 to January 2019 were collected to compare pregnancy outcomes between subjects with or without hyperuricemia (HUA). A smooth curve analysis was used to evaluate the relationship between uric acid levels and preterm delivery, low birth weight and smaller than gestational age. Logistic regression analyses were performed to identify risk factors for adverse pregnancy outcomes, and the interaction of the factors. During the third trimester of pregnancy, the uric acid levels of about 10% pregnant women were over 420 μmol/L. In those with HUA, the median neonatal birth weight was 2 590 (1 790, 3 410) g, the probability of premature birth was 49.81%, and the incidence of small than gestational age was 20.41%. These were significantly different from the women without HUA (the median neonatal birth weight: 3300 (2850, 3640) g; the probability of premature birth 23.09%; the incidence of small than gestational age 6.55%, respectively) (All <0.001). Maternal uric acid levels were negatively correlated with neonatal birth weight, and positively correlated with the risk of smaller than gestational age. It has a U-shaped association with the probability of premature birth, and the lowest probability of premature birth was at 200-400 μmol/L of the uric acid. Risks of low birth weight (adjusted =-5.22, 95%-6.46–3.99) and smaller than gestational age (adjusted =1.03, 95% 1.02-1.04) were increased in the function of uric acid levels. High uric acid, hypertension, oligoamnios and preeclampsia were important risk factors for the adverse pregnancy outcomes. The risk of preterm delivery and low birth weight enhanced when hyperuricemia combined with hypertension and preeclampsia. Serum uric acid level can be used as one of reliable markers for predicting adverse pregnancy outcomes, which might provide theoretical basis for clinical intervention in practice.

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