Abstract
OBJECTIVE: Gestational diabetes mellitus (GDM) increases the risk of fetal overgrowth as measured by two-dimensional ultrasonography. Whether fetal three-dimensional (3D) soft tissue and organ volumes provide additional insight into fetal overgrowth is unknown. RESEARCH DESIGN AND METHODS: We prospectively evaluated longitudinal 3D fetal body composition and organ volumes in a diverse U.S. singleton pregnancy cohort (2015-2019). Women were diagnosed with GDM, impaired glucose tolerance (IGT), or normal glucose tolerance (NGT). Up to five 3D ultrasound scans measured fetal body composition and organ volumes; trajectories were modeled using linear mixed models. Overall and weekly mean differences in fetal 3D trajectories were tested across glycemic status, adjusted for covariates. RESULTS: In this sample (n = 2,427), 5.2% of women had GDM, and 3.0% had IGT. Fetuses of women who developed GDM compared with NGT had larger fractional arm and fractional fat arm volumes from 26 to 35 weeks, smaller fractional lean arm volume from 17 to 22 weeks, and larger abdominal area from 24 to 40 weeks. Fetuses of women with IGT had similar growth patterns, which manifested later in gestation and with larger magnitudes, and had larger fractional lean arm volume. No overall differences were observed among thigh or organ volumes across glycemic status. CONCLUSIONS: Body composition differed in fetuses of GDM-complicated pregnancies, including larger arm and abdominal measures across the second and third trimesters. Patterns were similar in IGT-complicated pregnancies except that they occurred later in gestation and with larger magnitudes. Future research should explore how lifestyle and medication may alter fetal fat accumulation trajectories among hyperglycemic pregnancies.