Early pregnancy fasting plasma glucose and risk factors: impact on gestational diabetes mellitus and other adverse perinatal outcomes in singleton and twin pregnancies.

BACKGROUND

Gestational diabetes mellitus (GDM) poses distinct challenges across different pregnancy types, yet whether the roles of early metabolic markers and conventional risk factors vary between singleton and twin pregnancies remains unclear. This study sought to clarify the associations of early pregnancy fasting plasma glucose (FPG) and established risk factors with GDM and adverse perinatal outcomes in both pregnancy settings, with a particular focus on heterogeneity across the two groups.

METHODS

This retrospective study enrolled 5,532 singleton and 175 twin pregnancies from Ningjin County Hospital, Hebei Province, between January 1, 2019, and December 31, 2024. Data collected encompassed maternal baseline characteristics, early pregnancy FPG, GDM diagnosis (based on IADPSG criteria), and perinatal outcomes. Analytical approaches comprised multivariate logistic regression, interaction analysis, SHAP (Shapley additive explanations) analysis, and receiver operating characteristic (ROC) curve evaluation.

RESULTS

GDM incidence was significantly higher in twin than singleton pregnancies (30.29% vs. 21.98%, p < 0.05), as were adverse perinatal outcomes (preeclampsia, preterm birth, cesarean section; all p < 0.05). In singletons, early pregnancy FPG and all traditional risk factors correlated with GDM (p < 0.05); in twins, GDM history and PCOS associations with GDM were attenuated (not significant). Interaction analysis showed pre-pregnancy BMI and PCOS had stronger GDM predictive effects in singletons (p-interaction < 0.05). SHAP analysis confirmed lower contributions of GDM history and PCOS in twins, while early pregnancy FPG was the top predictor in both. Individual predictors had limited GDM predictive value (AUCs < 0.6), but combining early pregnancy FPG with all risk factors improved performance (AUCs: 0.783 for singletons, 0.784 for twins). Early pregnancy FPG and risk factors correlated with adverse outcomes, with more pronounced effects in twins.

CONCLUSION

Twin pregnancy is a high-risk condition for GDM and adverse outcomes. Pre-pregnancy BMI and PCOS are more strongly predictive of GDM in singleton pregnancies, while early pregnancy FPG serves as a universal predictor in both types. Individualized management strategies based on pregnancy type are warranted, with enhanced monitoring for twin pregnancies.