Factors associated with fetal growth and body composition as measured by ultrasound

Objective: This study seeks to determine which parental demographic and metabolic factors best correlate with fetal growth and body composition as estimated by ultrasound. Study Design: Thirty-one gravid patients had ultrasound estimates of fetal anthropometry in mid-third trimester. These measurements included estimated fetal weight, abdominal subcutaneous fat, and/or thigh subcutaneous fat thickness. Independent variables included diagnosis of gestational diabetes, parental demographic factors, neonatal sex, and late gestation estimates of carbohydrate metabolism. Results: In the multivariate stepwise model the strongest predictor of ultrasound estimated fetal weight was basal hepatic glucose production, followed by late gestation insulin sensitivity (total R2 = 0.27). The strongest predictors of abdominal subcutaneous fat thickness were weight gain and presence of gestational diabetes (total R2 = 0.25). Conclusion: Measures of maternal carbohydrate metabolism, rather than fat mass, explain sonographic measurements of fetal weight. We speculate that factors other than maternal carbohydrate metabolism further explain the variances of fetal adiposity. (Am J Obstet Gynecol 2001;185:1416-20.)