Abstract
Background: The presence of human milk banks allows the use of pasteurised donated breast milk in Neonatal Intensive Care Units (NICUs), which has been shown to have benefits for preterm infant recipients. There is, however, limited research on moderate to late (32/0 to 36/6 week) preterm infants as a NICU population. The use of a human milk analyser allows human milk banks to determine the nutrient composition of donated breast milk, which could further help improve the nutritional and growth status of infants through individualised fortification procedures.
Objectives: This study was in two phases: Phase one – to determine the macronutrient (fat, protein, carbohydrate), and energy content of donor breast milk from the Human Milk Bank, NICU, Christchurch Women’s Hospital; the impact that pasteurisation or maternal characteristics – such as gestational age or sex of the donor’s infant, lactation weeks of the donor, or whether the donor’s infant was currently preterm or term; and whether nutritional labelling of milk could help with individualised fortification procedures.
Phase two – to compare the nutritional status of moderate to late preterm infants (32/0 to 36/6 weeks) in the NICU at Christchurch Women’s Hospital prior to the Neonatal Human Donor Milk Bank opening (i.e. 2013) with matched donor milk recipient infants born after donor milk became available (i.e. 2016/2017), with respect to: demographics, nutrition interventions, and nutrition and growth outcomes.
Design: Phase one was an observational milk analysis study, using a human milk analyser to analyse 63 samples of donor breast milk from 27 donor mothers. Phase two was a retrospective comparison audit of 71 matched pairs of moderate to late (32/0 to 36/6 week) preterm infants from two cohorts, matched by gestational age, sex and twin status.
Results: For phase one, donated breast milk samples showed a wide variation in the concentration of energy and macronutrients. There was a significant (p≤0.001) but small (≤3%) difference between pre- and post-pasteurisation samples of donated breast milk for energy, fat and total carbohydrate. The main impact of maternal characteristics was the lactation weeks of the donor and whether the milk was term, which were both significantly inversely associated with protein concentration (both p<0.001). For phase two, there was a significant increase in the percentage of infants who were exclusively breast milk fed in the NICU (p<0.001), from 27% to 72%, and an increase in breastfeeding discharge rates from 21% to 40%, when donor breast milk was available. In the first week of life, energy and fat intakes were significantly greater for donor milk recipients by 4.9kcal/kg/day and 0.6g/kg/day respectively.
Conclusion: There is a large variation in the energy and macronutrient composition of breast milk donated by New Zealand women. This is very useful to know in order to tailor fortification of pasteurised donor milk for preterm NICU infants. These results also suggest that the use of pasteurised donor breast milk in the Christchurch NICU may be responsible for improved aspects of moderate to late preterm infants’ nutritional status.