Association of hyperuricemia with higher miscarriage rates and lower live birth rates in women undergoing IVF/ICSI.

Background: Hyperuricemia (HUA) has become popular globally, being an important risk factor for various metabolic diseases. Elevated serum uric acid (UA) levels cause adverse reproductive outcomes in women with polycystic ovary syndrome undergoing assisted reproductive technology (ART). However, its impact on reproductive outcomes in the general population is unknown.

Method: This retrospective study was conducted on a general population of infertility patients at a single center (March 2016-April 2023). Overall, 2189 first transfer cycles were screened for inclusion. HUA was defined as serum UA ≥ 360 µmol/L. Variables identified by LASSO regression analysis were entered into logistic regression models to calculate odds ratios. Generalized additive models were employed to examine the nonlinear relationship between serum UA as a continuous variable with outcomes. The primary outcome was live birth rate (LBR).

Results: Baseline characteristics revealed that HUA patients presented with significantly elevated metabolic parameters, including higher BMI, fasting glucose, lipid profiles, and greater prevalence of polycystic ovarian syndrome. Patients with HUA demonstrated significantly lower LBR and fertilization rates, along with higher miscarriage rates, while no significant differences were observed in oocyte retrieval numbers, embryo utilization rates, high-quality cleavage embryo formation, blastocyst formation rates, or clinical pregnancy rates (CPR). After adjusting for confounding variables, HUA remained a significant factor affecting LBR and miscarriage rate. Notably, the detrimental effects of HUA exhibited modality-specific patterns, with frozen-thawed embryo transfer (FET) cycles demonstrating greater vulnerability to HUA than fresh transfers. Among younger women, HUA independently predicted reduced LBR and increased miscarriage risk, with no significant association observed in those ≥ 35 years. And this effect remained significant in normal-weight (< 24 kg/m²) women but not in overweight individuals.

Conclusion: Elevated UA levels are linked to lower LBR and higher miscarriage risk in ART, especially in younger, non-obese women where HUA is an independent risk factor. Though not affecting embryo quality or implantation, HUA may impair pregnancy maintenance. Even in older or overweight patients, UA monitoring remains important. Routine assessment and tailored management-particularly greater attention to pregnancy loss and cautious use of programmed FET in poorly controlled cases-may help improve ART outcomes.