Intrauterine growth restriction and fetal body composition.

OBJECTIVE: To assess the differences in fetal body compartments between fetuses with normal growth and those with reduced intrauterine growth, during the third trimester, through ultrasonographic determination of subcutaneous tissue thickness (SCTT).
METHODS: Twenty-eight patients were enrolled into this case control study carried out at 30-31 weeks' gestation. Two study groups were matched for maternal age and pregestational body mass index: controls (n = 14) and intrauterine growth-restricted (IUGR) fetuses (n = 14). Routine ultrasound-derived biometric parameters (head circumference, abdominal circumference, femur length and humerus length) were measured. Additionally, the mid-arm fat mass and lean mass (MAFM and MALM), the mid-thigh fat mass and lean mass (MTFM and MTLM), the abdominal fat mass (AFM) and the subscapular fat mass (SSFM) were measured. The Mann-Whitney U-test and Student's t-test were used to compare the two groups.
RESULTS: The abdominal circumference and the humerus were significantly smaller in IUGR fetuses than in controls. Most of the SCTT values were different in the two groups. The SSFM (3.6 +/- 1.1 vs. 2.6 +/- 0.7 mm; P = 0.011), the AFM (5.1 +/- 0.7 vs. 4 +/- 1 mm; P = 0.01), the MAFM (3.5 +/- 0.9 vs. 2.2 +/- 0.8 cm2; P < 0.01) and MALM (2.1 +/- 0.4 vs. 1.7 +/- 0.5 cm2; P = 0.029) were all significantly greater in fetuses with normal development compared to those with growth restriction.
CONCLUSIONS: During the third trimester, SCTT (with the exception of MTFM and MTLM) is reduced in fetuses with IUGR. Furthermore, MALM is lower in growth-restricted fetuses, confirming that the parameters measured in this study are affected in IUGR fetuses. Our findings indicate that specific changes in fetal body compartments occur as a result of chronic metabolic impairment.