Postnatal weight trajectories drives beter head circumference growth in preterm infants ≤32 weeks: a multicenter Latin American cohort study.

BACKGROUND

Postnatal weight loss is nearly universal in preterm infants, and its relationship to head circumference (HC) growth remains incompletely characterized. Growth standards were recently updated with the Fenton 2025 charts, which modify Z-score parameters compared to the 2013 version.

OBJECTIVE

To evaluate the association between postnatal weight trajectory and HC growth from birth to discharge in preterm infants ≤32 weeks of gestation across a large multicenter Latin American cohort, using Fenton 2025 growth standards.

METHODS

This observational cohort study by secondary analysis of a prospective cohort study using data from EpicLatino, a quality improvement registry of 35 neonatal intensive care units (NICUs) across Latin America and the Caribbean (2015-2024). Infants ≤32 weeks admitted within 48 h of birth were included. The exposure was the change in weight Z-score (Fenton 2025) from birth to discharge, categorized into 10 groups at 0.4-unit intervals. The primary outcome was the change in HC Z-score (Fenton 2025). Multivariable linear regression with average marginal predictions was used, adjusting for gestational age, necrotizing enterocolitis (NEC), sepsis, SNAP-II score, length of stay, treated patent ductus arteriosus, Apgar score at 5 min, HC Z-score at birth, and outborn status.

RESULTS

3926 infants were included (analytical sample n = 3757). Median gestational age was 30 [IQR 29-32] weeks. Adjusted HC Δ Z-score ranged from -0.34 (95% CI -0.38 to -0.30) in infants with weight Δ Z-score >0, to -2.71 (95% CI -2.83 to -2.58) in those with weight Δ Z-score ≤-3.2. All group comparisons were statistically significant (p < 0.001). The model explained 37.6% of the variance in HC growth.

CONCLUSIONS

Postnatal weight trajectory is independently and progressively associated with HC growth in preterm infants ≤32 weeks across Latin America. Supporting weight recovery toward birth Z-score is a key nutritional target to promote adequate HC growth in the NICU.