Early-pregnancy fasting blood glucose and subsequent GDM define four distinct risk groups for adverse pregnancy outcomes: a cohort study of 15,245 women.

OBJECTIVE: To investigate the associations between a four-group classification based on early-pregnancy FBG and subsequent GDM status and maternal and neonatal outcomes, and to characterize the FBG-HDP dose-response relationship. METHODS: This retrospective cohort study included 15,245 women with singleton pregnancies. Participants were categorized into four groups based on early-pregnancy FBG (< 5.1 vs ≥ 5.1 mmol/L) and subsequent GDM status: Normoglycemia (normal FBG without GDM), GDM-Regression (elevated FBG without GDM), Late-onset GDM (normal FBG with GDM), and GDM-Maintained (elevated FBG with GDM). Multivariable logistic regression was used to estimate adjusted odds ratios (aOR) for outcomes. Restricted cubic spline regression was used to examine the dose-response relationship between FBG and HDP. RESULTS: The incidence of HDP increased progressively across groups: Normoglycemia 4.6%, GDM-Regression 6.9%, Late-onset GDM 8.1%, and GDM-Maintained 11.0% (P for trend <0.001). Compared with Normoglycemia, the aOR for HDP was 1.32 (95% CI: 1.03-1.68) for GDM-Regression, 1.53 (95% CI: 1.28-1.83) for Late-onset GDM, and 1.65 (95% CI: 1.23-2.18) for GDM-Maintained. GDM-Regression was associated with reduced SGA risk (aOR: 0.69, 95% CI: 0.53-0.87) but elevated LGA (aOR: 1.45, 95% CI: 1.21-1.74) and macrosomia (aOR: 1.62, 95% CI: 1.19-2.17) risks. GDM-Maintained showed the highest risks for LGA (aOR: 1.68), macrosomia (aOR: 1.81), preterm birth (aOR: 1.78), and neonatal asphyxia (aOR: 2.15). Restricted cubic spline analysis revealed a nonlinear relationship between FBG and HDP (overall P < 0.001; P for nonlinearity=0.036), with a statistical inflection point at 4.52 mmol/L. Stratified analyses showed consistent associations across age, BMI, ethnicity, and parity subgroups (all P for interaction >0.05). Sensitivity analyses using alternative FBG cutoffs (≥5.3 and ≥5.6 mmol/L) confirmed the robustness of these findings. CONCLUSIONS: The four-group classification based on early-pregnancy FBG and subsequent GDM status may be useful for stratifying the risk of adverse pregnancy outcomes. The observed inflection point warrants further investigation. These findings support the potential value of early-pregnancy glycemic assessment in refining risk characterization for pregnant women.