Mother's Own Milk and its Relationship to Growth and Morbidity in a Population-Based Cohort of Extremely Preterm Infants

OBJECTIVES: To evaluate the relationships between intake of mother's own milk (MOM), compared to intake of pasteurized donor milk (DM), and postnatal growth, incidence of retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD), in extremely preterm infants. METHODS: Swedish population-based cohort of surviving extremely preterm infants born 2004-2007. Exposure to MOM and DM was investigated from birth until 32 weeks postmenstrual age (PMA) in 453 infants. Primary outcome variables were change in z-score (Δ) from birth to 32 weeks PMA for weight, length and head circumference (HC). Secondary outcomes were incidence of ROP and BPD. Mixed models adjusting for confounders were used to investigate the association between exposures and outcomes. RESULTS: Infants' mean gestational age (GA) was 25.4 weeks. Unadjusted, MOM (per 10 ml/kg/d) was associated with Δweight and ΔHC with beta estimates of 0.03 z-score units (95% CI 0.02-0.04, p < 0.001) and 0.03 z-score units (95% CI 0.01-0.05, p = 0.003), respectively. After adjustment for predefined confounders the association remained significant for Δweight and ΔHC. A similar pattern was found between Δweight and each 10% increase of MOM. Unadjusted, a higher intake of MOM (ml/kg/d) was significantly associated to a lower probability of any ROP and severe ROP, however these associations did not remain in the adjusted analyses. No associations were found between MOM (ml/kg/d) and BPD. Moreover, no associations were found between DM and growth or morbidity outcomes. CONCLUSIONS: An increased intake of MOM, as opposed to DM (and not formula feeding), was associated with improved postnatal weight gain and HC growth from birth until 32 weeks PMA in extremely preterm infants. Interventions aiming at increasing early intake of unpasteurized MOM for extremely preterm infants should be encouraged