Association of maternal serum uric acid levels with LBW/SGA: a large retrospective cohort study

Background Elevated maternal serum uric acid (UA) levels were associated with adverse perinatal outcomes. This study aimed to examine the association between UA and the risk of low birth weight (LBW) / small for gestational age (SGA). Methods A cohort study of women delivered in Shanghai maternity hospital was included between 2017 and 2021. Electronic medical records were utilized to extract information and antenatal care records. The cut-off value of UA was 360 μmol/L. The outcome was LBW/SGA, with LBW defined as birth weight below 2500 g and SGA indicating birth weight below the 10th percentile of average weight for gestational age. The assessment of SGA was based on the Chinese standard curve for birth weight at various gestational ages. Univariate, multivariate logistic regression models, restricted cubic spline were used in this study, with adjustments made for confounding factors. Results Sixty-nine thousand six hundred seventy-four live births and singleton pregnancies were included. The ratio of LBW/SGA was 3.3%/9%. Maternal UA levels were significantly negatively correlated with birth weight. High UA levels were associated with high risk of LBW/SGA, especially in third trimester. In BMI < 25 group, the risk of LBW increased to 2.35-fold (95%CI, 1.66–3.31) in hyperuricemic group (UA > 360 μmol/L). The SGA risk was 1.66-fold (95%CI, 1.37–2.00). Gestational hypertension (GH) with hyperuricemica increased the risk of LBW (aOR = 4.00, 95%CI, 2.01–7.93) and SGA (aOR = 2.63, 95%CI, 1.83–3.78). Preeclampsia (PE) with hyperuricemia increased the risk of LBW (aOR = 1.38, 95%CI, 0.63–3.03) and SGA (aOR = 1.81, 95%CI, 1.18–2.78). In delivery gestational week (DGW) ≥ 37 group, if UA > 360 μmol/L, the incidence of LBW increased to 2.46-fold (95%CI, 1.62, 3.73) and the incidence of SGA increased to 1.52-fold (95%CI, 1.24, 1.87). In DGW < 37 group, if UA > 360 μmol/L, the incidence of LBW increased to 2.70-fold (95%CI, 1.92, 3.80) and the incidence of SGA increased to 2.13-fold(95%CI, 1.50, 3.02). Conclusions The study found an inverse correlation between UA levels and birth weight. High UA levels were associated with increased risk of LBW/SGA, particularly in third trimester. GH or PE complicated by hyperuricemia were found to have significantly higher risk of developing LBW/SGA. This relationship also existed in pregnant women with BMI < 25.