. - Higher serum uric acid (UA) has been associated with increased risk of type 2 diabetes mellitus. This cohort study examined whether there are any associations between serum UA in early pregnancy and the subsequent risk of gestational diabetes mellitus (GDM).

. - This cohort study was conducted in Shanghai, China, and included 85,609 pregnant women. Generalised additive models were used to estimate the associations of serum UA with risk of GDM.

. - The prevalence of GDM was 14.0% (11,960/85,609). Non-linear associations between serum UA and GDM risk were observed and these associations varied by gestational ages. Only elevated serum UA levels at 13-18 weeks gestation was associated with substantially increased risk of GDM. Analysis by UA quintiles at 13-18 weeks gestation showed the odds ratios for GDM were 1.11 (95%CI, 1.03-1.20) for the second, 1.27 (95%CI, 1.17-1.37) for the third, 1.37 (95%CI, 1.27-1.48) for the fourth and 1.70 (95%CI, 1.58-1.84) for the fifth quintile of serum UA in comparison with the first quintile. Stratified analysis showed the associations of serum UA with GDM were stronger among pregnant women aged 35 years or older.

. - We found higher serum UA at 13-18 gestational weeks was a risk factor for GDM. Our findings provide new evidence for the role of serum UA in the prevention and early intervention of GDM, and highlighted the need for monitoring serum UA at 13-18 gestational weeks.