Fetal frontal lobe development in gestational diabetes mellitus: a cross-sectional neurosonographic study

Objectives To evaluate the impact of gestational diabetes mellitus (GDM) on fetal frontal lobe development, as assessed by the anteroposterior frontal diameter (APFD) and its relationships with standard cranial biometric parameters. Methods This case–control study included 257 singleton pregnancies between 20 and 38 + 6 week’s gestation. Participants were divided into two groups: uncomplicated pregnancies (n=152) and pregnancies complicated by GDM (n=105). Ultrasound images were retrospectively analyzed to obtain APFD, occipitofrontal diameter (OFD), head circumference (HC), and transverse cerebellar diameter (TCD), as well as derived ratios (APFD/OFD, APFD/HC, and APFD/TCD). Clinical, metabolic, and perinatal data were collected. Results No significant differences were observed between groups in APFD (36.9 vs. 35.5 mm, p=0.086), TCD (40.1 vs. 38.6 mm, p=0.206), or in any of the evaluated ratios, including APFD/OFD (p=0.897), APFD/HC (p=0.702), and APFD/TCD (p=0.602). These findings remained consistent after stratification by type of glycemic control (diet vs. insulin). In contrast, the GDM group exhibited higher body mass index, fasting glucose levels, estimated fetal weight, and abdominal circumference (all p<0.05), as well as lower uterine and umbilical artery pulsatility indices. No clinically relevant differences were observed in head circumference or Apgar scores. Conclusions GDM was not associated with detectable alterations in fetal frontal lobe morphometry or its proportional relationships with global cranial measurements. These findings indicate no detectable differences in fetal frontal lobe morphometry using ultrasound parameters. However, no conclusions can be drawn regarding functional or neurodevelopmental outcomes.