Outcomes Associated With Type of Milk Supplementation Among Late Preterm Infants

To assess whether type of milk supplementation provided to breastfeeding late preterm infants was associated with hospital length of stay (LOS) or breastfeeding status at discharge.

Retrospective chart review.

Tertiary care teaching hospital in the southern United States.

Late preterm infants 35 0/7 to 36 6/7 weeks gestational age (N = 183) admitted to the mother-baby unit between November 1, 2014, and October 31, 2016.

The exposure of interest was type of milk supplementation, for example, expressed human milk, pasteurized donor human milk, and formula. Outcomes measured were LOS and breastfeeding status at discharge. Generalized Poisson regression models were used to compare LOS by type of milk supplementation. Modified Poisson regression models were used to estimate risk ratios and 95% confidence intervals for associations with breastfeeding status at discharge.

The LOS for breastfed infants supplemented with expressed human milk and/or pasteurized donor human milk did not differ significantly from exclusively breastfed infants who received no supplement. Exclusively formula-fed infants had longer LOS of 3.2 days compared with 2.6 days for exclusively breastfed infants (p = .001). Breastfed infants who received any formula supplementation were 16% less likely to continue breastfeeding until day of discharge compared with breastfed infants who received human milk supplementation (risk ratio = .84, 95% confidence interval [.77, .92]).

The high prevalence of supplementation among breastfeeding late preterm infants underscores the potential effect of type of milk supplementation on LOS and breastfeeding outcomes. Our findings suggest that human milk supplementation discourages transition to formula feeding before hospital discharge without increasing LOS.