IL-6 Predicts Poor Early Post-Natal Growth in Very Low-Birth-Weight Infants in a Low-Middle Income Setting

Background: Extra-uterine growth restriction (EUGR) is common in preterms and may be associated with elevated pro-inflammatory cytokines.

Objective: Describe postnatal growth in a cohort of very low-birth-weight (VLBW) infants and determine the association of interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-α) in umbilical cord blood with growth at 40 weeks and 12 months postmenstrual age (PMA).

Methods: Single-centre, prospective cohort study conducted from 1 June 2017 to 31 January 2019 with follow-up to 31 March 2020. Infants <1500 g at birth were enrolled, cord blood collected for IL-6 and TNF-α assays and postnatal care, including anthropometry, provided to 12 months PMA. Informed consent and ethics approval were obtained.

Results: In total, 279 patients were enrolled; 84 (30.1%) died before 12 months and 91 (32.6%) lost to follow-up. Anthropometry was available for 151 infants at 40 weeks and 105 at 12 months. Z-Scores at 40 weeks for males and females combined were -2.5, -2.1 and -1.2 for weight, length and head circumference. EUGR occurred in 103/113 (91.2%), 98/107 (91.6%) and 70/109 (64.2%) participants for weight, length and head circumference. Elevated IL-6 was associated with restricted weight (56.0 vs. 14.5 pg/ml, p = 0.02) and length (60.4 vs. 7.3 pg/ml, p = 0.01) at 40 weeks. There was no difference in IL-6 at 12 months and no difference in TNF-α at 40 weeks or 12 months.

Conclusion: The study reports significant EUGR. Elevated IL-6 was associated with growth restriction at 40 weeks but not 12 months PMA.