Fetal abdominal overgrowth is already present at 20-24 gestational weeks prior to diagnosis of gestational diabetes mellitus.

Fetal abdominal obesity (FAO) was detected at the time of gestational diabetes mellitus (GDM) diagnosis at 24-28 gestational weeks (GW) in older (≥ 35 years) and/or obese (≥ body mass index 25 kg/m2) women and persisted until delivery. We investigated whether FAO is already present at 20-24 GW. Medical records of 7820 singleton pregnancy including 384 GDM were reviewed. Fetal abdominal overgrowth was assessed by the fetal abdominal overgrowth ratios (FAORs) of the ultrasonographically estimated gestational age (GA) of abdominal circumference per actual GA by the last menstruation period, biparietal diameter or femur length, respectively. FAO was defined as FAOR ≥ 90th percentile. FAORs measured at 20-24 GW in older and/or obese but not in young and non-obese GDM subjects were significantly higher than those in NGT subjects. Relative to NGT subjects without FAO at 20-24 GW, odds ratios for exhibiting FAO at GDM diagnosis and large for gestational age in GDM with FAO at 20-24 GW were 10.15 and 5.57, and their primary cesarean delivery rate was significantly higher than those in GDM without FAO (44% vs. 29%). Earlier diagnosis and active interventions of GDM well before 20-24 GW might be necessary to prevent FAO in the older and/or obese women.