Ultrasound assessment of intrauterine growth restriction: relationship to neonatal body composition

OBJECTIVE: The objective of the study was to compare prenatal ultrasound parameters for intrauterine growth restriction (IUGR) with newborn percent body fat (% BF). STUDY DESIGN: This was a prospective study of 87 pregnancies followed with ultrasound. Subjects were categorized into 3 groups: estimated fetal weight (EFW) less than the 10th percentile, abdominal circumference (AC) less than the fifth percentile, and normal biometry. Neonatal % BF by air displacement plethysmography was compared between each group using multivariable analyses. RESULTS: The % BF in the EFW less than the 10th percentile group (5.1 +/- 2.9%) was significantly lower than either AC less than the fifth percentile (9.5 +/- 3.3%) or normal groups (11.6 +/- 5.6%). EFW less than the 10th percentile best predicted % BF by regression model. Neonatal morbidity was not significantly higher in the EFW less than the 10th percentile group. CONCLUSION: Newborn % BF was significantly lower in infants with EFW less than the 10th percentile compared with AC less than the fifth percentile, an intermediate finding. An AC less than the fifth percentile on ultrasound does not reflect the same severity of IUGR as EFW less than the 10th percentile.