Association of serum uric acid during pre-pregnancy with adverse pregnancy outcomes among women conceived by in-vitro fertilization: a retrospective cohort study

Maternal serum uric acid (UA) levels have been linked to adverse pregnancy outcomes, but no studies have yet examined this association in women undergoing assisted reproductive technology. This study aimed to investigate the relationship between pre-pregnancy UA levels and adverse pregnancy outcomes in women conceived via in vitro fertilization and embryo transfer (IVF-ET). This retrospective cohort study included 2 111 singleton pregnancies conceived via IVF-ET, delivered at Peking University Third Hospital between 1 January 2017 and 30 April 2022. Restricted cubic splines were used to test nonlinear relationships between serum UA during pre-pregnancy and adverse outcomes, and multivariable logistic regression to calculate odds ratio (OR) and 95% confidence interval (CI). Of the 2 111 women, no significant associations were found between pre-pregnancy UA levels and preeclampsia, preterm birth, or macrosomia. However, a J-shaped relationship was observed for gestational diabetes mellitus (GDM) and low birth weight (LBW), and an inverse U-shaped relationship for gestational hypertension (GH). Reflecting these distinct non-linear topologies, statistically significant peak risks were observed and reported at different strata: women in the higher quintile (4th quintile) of UA had a 3.20-fold increased risk of GH (adjusted OR 3.20, 95% CI 1.23, 8.33) and a 1.38-fold increased risk of GDM (adjusted OR 1.38, 95% CI 1.01, 1.88) compared with the lowest quintile. Conversely, the risk of LBW accelerated sharply and peaked at the highest quintile (5th quintile) (adjusted OR 1.98, 95% CI 1.11, 3.54). In the subgroup analysis, the positive association between pre-pregnancy UA and LBW was more pronounced among patients with day 5 embryo transfer. These findings suggest that optimizing serum UA levels in women planning pregnancy, particularly those undergoing IVF-ET, may have important clinical implications for improving pregnancy outcomes.