Fig. 5. Change in head circumference z-scores in very low birth weight infants with surgical necrotizing enterocolitis or spontaneous intestinal perforation from birth through hospital discharge and follow up at 24 months corrected age.

Z-scores were calculated using the Fenton growth chart through 50 weeks corrected age and World Health Organization growth charts thereafter [9, 10]. Linear mixed models were used to compare longitudinal head circumference outcomes by surgical necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) groupings. Modeled means and 95% confidence intervals were calculated by NEC/SIP status and study visit.