Association of Maternal Serum Uric Acid and Cystatin C Levels in Late Pregnancy with Adverse Birth Outcomes: An Observational Cohort Study in China

OBJECTIVE: To investigate the associations between serum uric acid (UA) and cystatin C (CysC) levels in late pregnancy with major unfavorable birth outcomes. METHODS: We retrospectively analyzed the maternal UA and CysC levels during late pregnancy and their relationship with unfavorable birth outcomes in a Chinese population (n = 11,580). RESULTS: Women with the highest quartile of UA had higher risks of low birth weight (LBW) and small for gestational age (SGA) babies and a lower risk of preterm birth (PTB) compared to women with the lowest quartile [for LBW, adjusted-odds ratio (OR) = 2.63, 95% CI: 1.76, 3.95; for SGA, adjusted-OR = 2.11, 95% CI: 1.73, 2.57; for PTB, adjusted-OR = 0.55, 95% CI: 0.45, 0.69; all P for trend <0.001]. Compared to women in the lowest quartile of CysC, higher risks of macrosomia and large for gestational age (LGA) and lower risks of PTB and SGA were observed for those in the highest quartile (for macrosomia, adjusted-OR = 2.01, 95% CI: 1.60, 2.51; for LGA, adjusted-OR = 1.97, 95% CI: 1.67, 2.32; for PTB, adjusted-OR = 0.32, 95% CI: 0.26, 0.41; all P for trend <0.001; for SGA, adjusted-OR = 0.78, 95% CI: 0.64, 0.96; P for trend <0.05). CONCLUSION: This study reports the associations of maternal UA and CysC with adverse birth outcomes, and suggests that routine determination of maternal UA and CysC in late pregnancy is beneficial for assessing the risks of these outcomes.