When a mother's own breast milk is not available, feeding preterm or low birth weight infants with formula rather than donor breast milk probably increases rates of weight gain, linear growth and head growth (moderate-certainty evidence) but probably makes little or no difference to survival or longer‐term growth and development (moderate-certainty evidence). Infants fed with formula rather than donor breast milk probably have a higher risk of developing necrotising enterocolitis, a severe gut disorder (moderate-certainty evidence). Cochrane Review (published July 2019); 12 studies with 1871 preterm or low birth weight infants, comparing feeding on formula (term or preterm) with donor breast milk (unfortified or fortified).