Fetal abdominal subcutaneous tissue thickness measured by ultrasound at term is associated with birth weight and mode of delivery.

PURPOSE: To determine if measurement of fetal abdominal subcutaneous tissue thickness (FASTT) at term can predict birth weight, mode of delivery and perinatal outcome. METHODS: A prospective study with 352 normal, singleton pregnancies in the vertex presentation examined with real-time ultrasound at 37-39 weeks' gestation. RESULTS: FASTT was positively correlated with birth weight (Pearson's, r = 0.784, p < 0.001). Fetuses with low FASTT were more likely to be delivered through normal vaginal delivery (7.8 +/- 0.1 mm), while higher FASTT was correlated with operative vaginal delivery (7.9 +/- 0.2 mm) and cesarean section (8.6 +/- 0.3 mm) (ANOVA, p = 0.034). In contrast, FASTT was not correlated with intrapartum CTG, labor duration and Apgar scores. CONCLUSIONS: In normal pregnancies, FASTT at term is positively associated with birth weight. With increasing FASTT the likelihood of operative vaginal and cesarean delivery increases. FASTT is not associated with perinatal outcome.