Association of serum biomarkers of dietary purine intake with glycaemic control and risk of preterm birth: two prospective cohort studies among pregnant women

BACKGROUND: To examine serum purine metabolites as biomarkers of maternal dietary purine intake and their associations with glycaemic control and preterm birth during pregnancy. METHODS: We included 1480 pregnant Chinese women with gestational diabetes mellitus (GDM) from the Westlake Precision Birth Cohort (WeBirth) at mid-pregnancy, divided into discovery (n = 1230) and internal validation (n = 250) subcohorts. Linear regression was used to assess associations between serum metabolites, dietary purine intake, and continuous glucose monitoring (CGM) metrics. A purine score was developed and evaluated for associations with glycaemic control and preterm birth, with replication in 936 pregnant women from the Tongji-Huaxi-Shuangliu Birth Cohort (THSBC). FINDINGS: Serum purine level was associated with dietary purine intake and with the mean of daily difference (β = 0.096 [95% CI, 0.038, 0.15]). The association between higher serum purine and preterm birth risk in the WeBirth cohort (OR = 1.29 [95% CI, 1.06, 1.52]) was replicated in the THSBC cohort. Early-pregnancy serum purine also predicted GDM risk (OR = 1.38 [95% CI, 1.13, 1.63]) in the THSBC. A purine score comprising purine, adenine, 6-O-methylguanine, and uric acid showed consistent associations with glycaemic variability and preterm birth across both cohorts. INTERPRETATION: Reflecting dietary purine intake, serum purine level and purine score are associated with greater glycaemic variability and higher preterm birth risk. Monitoring dietary purine intake may improve glycaemic control in GDM and prevent pregnancy complications.