Objective:To investigate the factors affecting the delivery of macrosomic infants in pregnant women with gestational diabetes mellitus, and utilize data to construct a nomogram model and validate it.Methods:A total of 1 493 pregnant women with gestational diabetes mellitus who received treatment at Shaanxi Provincial People's Hospital from January 2023 to January 2024 were included in this study. A retrospective study was conducted to analyze the proportion of pregnant women with gestational diabetes mellitus who delivered macrosomic infants. The influential factors in pregnant women with gestational diabetes who delivered macrosomic infants were analyzed using both univariate and multivariate analyses. A predictive model for macrosomia in pregnant women with gestational diabetes mellitus was established, and its predictive efficiency was evaluated.Results:Among the 1 493 pregnant women with gestational diabetes mellitus included in this survey, 51 delivered macrosomic infants, accounting for 3.42%. Univariate analysis revealed that weight gain during pregnancy [(14.11 ± 3.25) kg vs. (10.62 ± 2.72) kg, t = 8.94], pre-pregnancy body mass index [(24.31 ± 2.51) kg/m2 vs. (23.25 ± 2.13) kg/m2, t = 8.94], gestational week [(39.14 ± 0.42) weeks vs. (38.92 ± 0.51) weeks, t = 3.04], fasting blood glucose [(5.15 ± 0.41) mmol/L vs. (4.75 ± 0.35) mmol/L, t = 7.97], blood glucose level during the oral glucose tolerance test at 0 hours [(5.71 ± 0.42) mmol/L vs. (5.49 ± 0.41) mmol/L, t = 3.76], and insulin resistance index [(0.54 ± 0.13) vs. (0.41 ± 0.10), t = 9.02] had a significant impact on the delivery of macrosomic infants (all P < 0.05). Multivariate logistic analysis indicated that weight gain during pregnancy, fasting blood glucose, and insulin resistance index were independent risk factors for delivering macrosomic infants in pregnant women with gestational diabetes mellitus ( OR = 1.685, 27.113, 25.816, all P < 0.05). The multivariate logistic regression model demonstrated good goodness of fit (Hosmer-Lemeshow χ2 = 10.34, P > 0.05). Based on the factors identified through multivariate analysis, a nomogram risk model was constructed, yielding a C-index of 0.742. The independent risk factors from the logistic regression model and their prediction probabilities were utilized to generate the receiver operating characteristic curve for predicting the likelihood of delivering macrosomic infants among pregnant women with gestational diabetes mellitus. The areas under the curve were 0.815, 0.779, 0.795, and 0.938, respectively. Conclusion:The predictive model established based on weight gain during pregnancy, fasting blood glucose levels, and the insulin resistance index demonstrates significant predictive value for the delivery of macrosomic infants in pregnant women with gestational diabetes mellitus.