Postnatal growth in extremely low birth weight newborns: nature or nurture?

The association between antenatal corticosteroids exposure and postnatal growth in infants born between 23 and 29 weeks of gestation

OBJECTIVE

To assess the association between antenatal corticosteroids exposure and postnatal growth in infants born at 23-29 weeks' gestation.

STUDY DESIGN

This retrospective study used data from the Pediatrix Clinical Data Warehouse. Maternal-infant dyads from 2018 to 2020 were included. Inverse propensity weighting (IPW) was applied to balance pre-treatment confounders. Primary outcomes included postnatal weight, length, and head circumference growth trajectory percentiles.

RESULT

The unadjusted cohort consisted of 11,912 dyads. After IPW adjustment, there were 23,231 dyads. Exposed infants showed higher postnatal trajectory percentiles for weight (by 3.4%), length (by 1.8%), and head circumference (by 2.5%) when compared to non-exposed infants. The positive association between antenatal corticosteroids and postnatal growth was only observed in infants not exposed to preeclampsia/eclampsia/HELLP syndrome or without fetal growth restriction.

CONCLUSION

Antenatal corticosteroids exposure is associated with better postnatal growth. The study is limited by its retrospective nature.

Dilemmas in human milk fortification

Fortification of human milk is the standard of care for very low birth weight (VLBW) infants and is required to support adequate postnatal growth and development. Achieving adequate growth velocity and preventing growth faltering is critical for the developing neonatal brain and optimizing long-term neurodevelopmental outcomes. Mother's milk is the gold standard nutrition to feed preterm infants, however, it does not provide the nutrients needed to support the growth of VLBW infants. After the decision is made to use mother's milk (if available) or alternatively, donor human milk, many dilemmas exist with regards to additional treatment decisions surrounding the type of fortification to use, when to fortify, and the duration of fortification. In this article, we will review the differences in mother's milk compared to donor milk, the different types of human milk fortifiers, the optimal timing of fortification, and discuss when to discontinue human milk fortification.

Sex differences in postnatal weight gain trajectories of extremely preterm newborns

OBJECTIVE

Both postnatal growth and sex play a crucial role in long-term outcomes of extremely preterm newborns (EPNs), but the relationship between sex and postnatal growth is not clear. This study aims to assess sex differences in weight trajectories.

STUDY DESIGN

Weight data in the first 200 days of life from 4327 EPNs were used for generalized additive mixed modeling. We considered gestational age and sex as fixed-effects, and included random intercepts and random slopes for postnatal age. We assessed interactions between fixed-effects and postnatal age.

RESULTS

Male EPNs had higher predicted weight trajectories than females. Weight z-score trajectories decreased in both sexes before term-equivalent age comparably, but females showed faster increases afterward. Although weight gain velocity was comparable between both sexes, weight gain velocity in male EPNs was lower compared to the corresponding reference values from the 2013 Fenton growth charts, which explained slower z-score rises.

CONCLUSION

Sex disparity exists in postnatal weight gain trajectories of EPNs after reaching the term-equivalent age.