Static and longitudinal extrauterine growth restriction in very low birth weight infants: prevalence and associated factors.

OBJECTIVES

Extrauterine growth restriction (EUGR) occurs when preterm infants fail to achieve expected intrauterine growth rates. EUGR is classified as static (body weight < 10th percentile at 36 weeks postmenstrual age (PMA) or longitudinal (weight z-score decline > 1 standard deviation from birth to 36 weeks PMA). This study aimed to determine the prevalence of each type and identify associated factors.

METHODS

This retrospective cohort study included very low birth weight (VLBW) infants admitted to a tertiary-level NICU between January 2020 and December 2023. Infants who died, were transferred before 36 weeks PMA, or had chromosomal or major anomalies were excluded.

RESULTS

Of 107 infants, 55 (51.4%) had static EUGR and 35 (32.7%) had longitudinal EUGR. Multivariable analysis identified SGA as the only significant factor associated with static EUGR (aOR 9.01, 95% CI 2.08-39.08, p = 0.003). Delayed achievement of 120 mL/kg/day after day of life 10 showed a positive association with static EUGR but did not reach significance (aOR 2.57, 95% CI 0.93-7.13, p = 0.069). In contrast, delayed full enteral feeding was the only significant factor associated with longitudinal EUGR (aOR 3.98, 95% CI 1.48-10.68, p = 0.006). Agreement between definitions was weak (κ = 0.186, p = 0.019).

CONCLUSION

Static EUGR was strongly associated with SGA status at birth, whereas longitudinal EUGR identified a partially distinct subgroup of infants. Delayed achievement of full enteral feeding was significantly associated with longitudinal EUGR. This finding warrants cautious interpretation, as delayed enteral feeding may serve as a marker of illness severity rather than a direct causal factor.