Association Between Maternal Fasting Plasma Glucose Value and Fetal Weight Among Singletons of Mothers with Gestational Diabetes Mellitus

Purpose: Infants with macrosomia are more likely to be born to mothers with gestational diabetes mellitus (GDM). This study aimed to investigate the associations between maternal blood glucose levels and fetal weight, placental weight, and risk of macrosomia in mothers with GDM.Patients and Methods: This retrospective study included 3211 singletons of mothers with GDM at the Shanghai First Maternity and Infant Hospital between January 2017 and December 2019. All women underwent an oral glucose tolerance test (OGTT) during the 24-28 weeks gestation period. Data on fetal and placental parameters were collected at delivery. Multiple linear regression models were used to evaluate the associations of maternal blood glucose levels with fetal weight and placental weight, while multiple logistic regression model was used to estimate the association between maternal blood glucose levels and the risk of macrosomia.Results: The prevalence of GDM in our study was 7%. Fasting plasma glucose (FPG) was positively correlated with fetal weight (r2=0.0329, P<0.001), and macrosomia risk (odds ratio [OR], 2.42; 95% confidence interval [CI], 1.93-3.04; P<0.001). After adjusting for gestational age, the result remained significant (OR, 2.67; 95% CI, 2.11-3.38; P<0.001). In contrast, there was no significant relationship between 1-h plasma glucose (1hPG) or 2-h plasma glucose (2hPG) and fetal weight (P=0.18, P=0.46). Additionally, 1hPG or 2hPG was not strongly associated with macrosomia risk (OR, 0.95; 95% CI, 0.85-1.05; P=0.32 vs OR, 0.94; 95% CI, 0.85-1.05; P=0.28). Maternal blood glucose levels did not affect placental weight. The associations were similar in women carrying male and female fetuses.Conclusion: Maternal fasting plasma glucose levels were strongly associated with increased birth weight and macrosomia risk. Our findings suggest that fasting plasma glucose may predict birth weight.