Mother’s Own Milk Associated With Postnatal Growth in Extremely Preterm Infants

Investigators assessed the effects of intake of mother’s own milk vs pasteurized donor milk on postnatal outcomes in extremely preterm infants.

Study data published in the Journal of Pediatric Gastroenterology and Nutrition suggest that increased intake of mother’s own milk (MOM) compared with intake of pasteurized donor milk (DM) is associated with postnatal weight gain in extremely preterm infants.

This population-based cohort study of surviving preterm infants was conducted in Sweden between 2004 and 2007. Per standards of care in Sweden, extremely preterm infants are offered pasteurized DM as a complement to MOM until at least 32 weeks postmenstrual age (PMA), after which DM is replaced by preterm formula.

Investigators sought to examine the relationship between MOM and DM intake and postnatal outcomes. The primary exposure was mean daily intake of MOM compared with DM. Milk intake was rescaled into increments of 10 mL/kg/day for analytic purposes.

The primary outcome variables were changes in weight, length, and head circumference from birth to 32 weeks PMA. Outcome metrics were converted to z-scores using gestational age and sex-specific Fenton preterm infant growth references. Secondary outcomes were incidence of retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD). Mixed models were used to assess the relationship between MOM exposure and growth and morbidity outcomes.

Exposure to MOM and DM were ultimately investigated in 453 infants. Mean gestational age was 25.4 weeks. Overall, 50 infants (11%) received <20% MOM by volume, 100 (22%) received 20-80% MOM by volume, and 303 (63%) received >80% MOM by volume.

MOM intake was positively associated with increases in weight and height circumference in univariable models. This association remained significant in models adjusted for gestational age, birth anthropometry z-score, mechanical ventilation, postnatal steroid treatment, health care region, and proportion of parenteral fluids to total fluids. Specifically, each increase of 10 mL MOM per kg/day was associated with an increase of 0.02 (95% CI, 0.01-0.03; P <.001) z-score units for weight and 0.02 (95% CI, 0.00-0.04; P =.049) z-score units for head circumference through 32 weeks PMA.

In univariable models, a negative association was observed between MOM and any ROP, severe ROP, and receiving ROP treatment. The negative association between MOM intake and severe ROP remained significant after adjustments for gestational age, birth weight z-score, mechanical ventilation, postnatal steroid treatment, and health care region (odds ratio [OR], 0.94; 95% CI, 0.90-0.99; P =.010).

MOM intake was not significantly associated with BPD in any models. Further, DM was not associated with changes in weight, length, or head circumference in univariable modeling. DM intake was also not correlated with reduced likelihood of ROP or BPD.

Study limitations include standard of care differences between study regions and the inability to determine the amount of fortification used in MOM and DM. Additionally, the nutritional care of extremely preterm infants during the study period (2004-2007) differs from standards applied today. Further research is necessary to better understand the respective effects of MO compared with DM on postnatal growth.

These results suggest that increased emphasis on providing MOM may promote growth and prevent morbidity in extremely preterm infants. “We found that MOM, as compared with DM, was associated with improved postnatal weight gain and [head circumference] growth in this national population-based cohort of extremely preterm infants,” investigators wrote. “It is essential for neonatal health care professionals to include interventions that aim to increase the early intake of unpasteurized MOM in the care of extremely preterm infants.”

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 


Lund AM, Domellöf M, Pivodic A, Hellström A, Stoltz Sjöström E, Hansen-Pupp I. Mother’s own milk and its relationship to growth and morbidity in a population-based cohort of extremely preterm infants. J Pediatr Gastroenterol Nutr. 2022;74(2):292-300. doi: 10.1097/MPG.0000000000003352