Subcutaneous fat in the fetal abdomen as a predictor of growth restriction

To determine if measuring fetal abdominal fat antenatally using ultrasound can predict fetal growth restriction (FGR).

One hundred thirty-seven unselected women with singleton pregnancies had serial ultrasound scans at 20, 26, 31, and 38 weeks' gestation. Subcutaneous fat in the fetal abdomen was measured using the same section as the abdominal circumference (AC). Outcome measures were birth weight, neonatal morbidity, and ponderal index.

Infants with subcutaneous fat less than 5 mm at 38 weeks (n = 51) were almost five times more likely to have a birth weight below the 10th centile than those with subcutaneous fat of 5 mm or more (n = 75). The incidence of neonatal morbidity was significantly higher in infants with subcutaneous fat less than 5 mm, compared with those with subcutaneous fat of 5 mm or more (20% versus 8%, P < .05). Decreased subcutaneous fat was also associated with a high prevalence of low ponderal index, regardless of birth weight category.

Measurement of fat in the abdominal wall is a simple technique with a sensitivity for predicting low birth weight similar to that of conventional sonography and might potentially predict FGR irrespective of fetal weight.