Neonatal steroid exposure and body composition in preterm infants at discharge

Corticosteroids are frequently used in very preterm (VPT) infants. Corticosteroids can increase adiposity and decrease lean mass, with unclear effects in VPT infants. We hypothesized that corticosteroid exposure in VPT infants would be associated with increased fat mass (FM), %FM, and decreased fat-free mass (FFM).

This prospective study included 62 infants <32 weeks' gestational age (GA) or <1500 grams birth weight (BW). Body composition was obtained using bioelectrical impedance analysis (BIA) at neonatal intensive care unit (NICU) discharge. We estimated FFM from BIA, calculated FM and %FM, and determined z-scores for postmenstrual age and sex. Body composition indices in steroid-exposed and non-steroid-exposed subjects were compared using Mann-Whitney U tests.

The mean GA was 28 ± 2.5 weeks, and the mean BW was 1089±401grams. Fourteen infants (22.5%) had steroid exposure, which was associated with significantly higher FM, %FM, and FFM. However, no significant differences in FM, %FM, and FFM z-scores were observed.

Steroid exposure was associated with differences in the body composition of VPT infants at NICU discharge. However, after adjusting for post-menstrual age and sex using z-scores, the difference was no longer significant, likely reflecting the longer hospitalization and later postmenstrual age at discharge in the steroid-exposed cohort.

Corticosteroids are regularly utilized in neonatal intensive care units, and the impact of these medications on body composition in preterm neonates is unclear. Our study found no significant difference in fat mass (FM), %FM, or fat-free mass (FFM) z-scores between very preterm (VPT) infants with and without steroid exposure. Our study highlights the feasibility of using bioelectrical impedance analysis (BIA) to assess body composition in the NICU.