Ultrasound Evaluation of Fetal Growth Patterns in Antenatal Women with Gestational Diabetes Mellitus

Abstract

Background: Gestational Diabetes Mellitus (GDM) is a major metabolic complication of pregnancy and is strongly associated with fetal overgrowth and large-for-gestational-age (LGA) infants. Even mild maternal hyperglycemia alters fetal fat deposition, increasing the risk of macrosomia and related perinatal complications including shoulder dystocia, neonatal hypoglycemia, operative delivery, and birth trauma. Serial ultrasonographic assessment of fetal biometry plays a critical role in identifying accelerated growth patterns and guiding clinical management.

Methods:This hospital-based case–control study included 150 antenatal women between 28–40 weeks of gestation, comprising 75 women diagnosed with GDM using DIPSI criteria and 75 normoglycemic controls. Maternal demographic and metabolic characteristics were recorded. Fetal biometric parameters—biparietal diameter, head circumference, abdominal circumference, femur length, and estimated fetal weight—were measured and plotted against WHO growth standards. Fetuses were categorized as small-, appropriate-, or large-for-gestational-age. Among GDM mothers, treatment modality (meal plan, oral hypoglycemic agents [OHA], or insulin) and glycemic control (FBS and PPBS levels) were analyzed. Logistic regression models were applied to identify independent predictors of LGA.

Results:Women with GDM had significantly higher pre-pregnancy BMI and a greater prevalence of family history of diabetes and previous GDM. Fetuses of GDM mothers demonstrated significantly higher abdominal circumference and estimated fetal weight compared to controls. LGA prevalence was nearly threefold higher in GDM pregnancies (29.3%) compared to normoglycemic pregnancies (8.0%). Among GDM mothers, LGA occurred in 14.3% of diet-controlled cases compared to 37.5% in the OHA group and 39.1% in the insulin group (p=0.002). Mothers requiring pharmacologic therapy had higher mean FBS (98–104 mg/dL) and PPBS (142–158 mg/dL), demonstrating nearly a threefold increase in LGA risk with suboptimal glycemic control. Serial growth assessment revealed that significant divergence in abdominal circumference and fetal weight became evident after 32 weeks of gestation. On multivariate analysis, current GDM, elevated pre-pregnancy BMI, and increased fetal abdominal circumference remained independent predictors of LGA.

Conclusion:Gestational diabetes significantly increases the risk of fetal overgrowth, particularly when glycemic control is suboptimal. Elevated pre-pregnancy BMI independently contributes to LGA risk, underscoring the importance of preconception weight optimization and early metabolic screening. Strict glycemic control and serial third-trimester ultrasound monitoring—especially fetal abdominal circumference tracking—are essential strategies to reduce LGA-associated perinatal complications.