Abstract
The preterm baby is born at a critical period for the growth and development of the gastrointestinal and neuromotor systems. Breast milk is the food of choice for infants during the first months of life, as it provides multiple short- and long-term benefits to preterm and sick newborns. Despite this, breastfeeding is often nutritionally insufficient, requiring the addition of fortifiers. In other cases, it is important to ensure the necessary nutrients and calories, which can be provided by formula milk or pasteurized and fortified donated human milk. However, the specific guidelines for the use of formula milk have not yet been determined. Therefore, a systematic search was considered necessary in order to identify the effects of feeding with formula milk in preterm infants. A systematic search in Scopus, Medline, Pubmed, Cinahl, ClinicalTrials and Web of Science with the terms Infant Formula and Infant Premature was conducted. A total of 18 articles were selected, of which, eight were experimental and ten were observational studies. Among the objectives of the analyzed investigations, we distinguished nine that compared the effects of feeding with formula milk, breast milk and donated human milk, five that evaluated the effects of different compositions of formula milk and/or fortifiers and four investigations that compared the effects of formula milk and donated human milk. In conclusion, when breast milk is insufficient or unavailable, formula milk is a good nutritional option, due to its higher caloric density and protein content. Nevertheless, the preterm infant's diet should incorporate breast milk to reduce the incidence of morbidities such as necrotizing enterocolitis and sepsis (related to hospital handling of fortifiers and formula milk).