Systemic Inflammation in the First 2 Weeks After Birth as a Determinant of Physical Growth Outcomes in Hospitalized Infants With Extremely Low Gestational Age.

Objective To examine associations of systemic inflammation with growth outcomes at neonatal intensive care unit (NICU) discharge/transfer among infants with extremely low gestational ages. Study design We studied 850 infants at born 23-27 weeks of gestation. We defined inflammatory protein elevation as the highest quartile of c-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-∝), or interleukin 8 (IL-8) on postnatal days 1, 7, and 14. We compared z-scores of weight, length, and head circumference at NICU discharge/transfer between infants with vs without inflammatory protein elevation, adjusting in linear regression for birth size z-score, sex, gestational age, diet, co-morbidities, medications, and length of hospitalization. Results Mean gestational age was 25 weeks (range, 23-27) and birth weight z-score 0.14 (range, -2.73, 3.28). Infants with CRP elevation on day 7 had lower weights at discharge/transfer (-0.17 z-scores, 95% CI -0.27, -0.06) than infants without CRP elevation; with similar results on day 14. Infants with CRP elevation on day 14 were also shorter (-0.21 length z-scores, 95% CI -0.38, -0.04), and had smaller head circumferences (-0.18 z-scores, 95% CI -0.33, -0.04) at discharge/transfer. IL-6 elevation on day 14 was associated with lower weight (-0.12, 95% CI -0.22, -0.02); IL-6 elevation on day 7 was associated with shorter length (-0.27, 95% CI -0.43, -0.12). TNF-∝ and IL-8 elevation on day 14 were associated with lower weight at discharge/transfer. Conclusion Postnatal systemic inflammation may contribute to impaired nutrient accretion during a critical period in development in infants with extremely low gestational ages.