Fasting plasma glucose and fetal ultrasound predict the occurrence of neonatal macrosomia in gestational diabetes mellitus.

Objective: The cause of fetal overgrowth during pregnancy is still unclear. This study aimed to analyze and predict the risk of macrosomia in pregnant women with gestational diabetes mellitus (GDM).

Methods: This study was a retrospective study collected from October 2020 to October 2021. A total of 6072 pregnant women with a routine 75-g oral glucose tolerance test (OGTT) during 24-28 gestational weeks were screened. Nearly equal numbers of pregnant women with gestational diabetes and with normal glucose tolerance (NGT) were included in the study. Multivariate logistic regression analysis and receiver operating characteristic (ROC) curve were performed to determine the index and inflection point for predicting macrosomia occurrence.

Results: The data of perinatal outcomes of 322 GDM and 353 NGT who had given birth to single live babies at term were analyzed. We found that significant cut-off values for the prediction of macrosomia are 5.13mmol/L in fasting plasma glucose (FPG), 12.25kg in gestational weight gain (GWG), 3,605g in ultrasound fetal weight gain (FWG) and 124mm in amniotic fluid index (AFI).The area under the ROC curve of this predictive model combined all variables reached 0.953 (95% CI: 0.914 ~ 0.993) with a sensitivity of 95.0% and a specificity of 85.4%.

Conclusions: FPG is positively associated with newborn birth weight. An early intervention to prevent macrosomia may be possible by combining maternal GWG, FPG, FWG, and AFI in gestational diabetes.