Donor Human Milk
Human milk given by a donor to a human milk bank can be tested for bacterial load, pasteurised and provided for babies who are temporarily or permanently unable to receive their mother's milk, as recommended by NICE. This may be because of a maternal absolute contraindication to breastfeeding, such as bilateral mastectomy or ongoing cancer treatment, or because milk supply is not enough to cover their baby or babies' needs. Human milk bank donors are screened for blood-borne viruses and can only be taking medications where no caution is advised relating to breastfeeding (stricter criteria than would be applied to someone breastfeeding their own baby).
In the UK donated milk availability is extremely variable across the country. In some areas babies in the community, on postnatal wards and on neonatal units can access donated milk whereas in others only very preterm babies on neonatal units are given donor milk, and in many areas there is no availability at all.
The WHO recommends that donor milk should be used in preference to formula for low birthweight babies. The expansion of milk banking in Brazil shows that availability and cost barriers can be overcome if the political will is there.
The pasteurisation process reduces some of the immunological properties of human milk - for example around 30% reduction in IgA concentration and activity, considerable loss of lactoferrin, cytokines, growth factors, hormones and antioxidant capacity. Nutritional content is not generally affected, although the loss of lysozyme activity may affect fat absorption.
A recent randomised controlled trial has shown that the rate of any or severe necrotising enterocolitis is reduced with use of fortified donor milk group compared to preterm formula as a supplement to maternal milk when insufficient - Cochrane review reports relative risk of NEC of 1.6 in this context.
Occasionally no maternal milk is available and in this setting randomised controlled trials of preterm formula versus donor milk as sole diet also showed an increased risk of invasive infection with preterm formula (relative risk 1.4). The Cochrane review reports that there is no difference in long term neurodevelopmental outcome between donor milk and preterm formula and that growth is higher in the formula group, but more recent RCT of appropriately fortified donor milk did not show a growth deficit.
There is little research on the use of donor human milk outside the context of prematurity, however preliminary work has shown normal growth patterns in a small number of babies drinking exclusive donor milk in the community via the Hearts Milk Bank (poster presentation 2019). One study also noted that mothers view donor milk differently to formula when used on the postnatal ward as a supplement - donor milk is seen as temporary whereas formula is seen as an ongoing plan, and donor milk is seen as 'healthier'.