RESUMO
BACKGROUND: Breastfeeding maintains the maternal-fetal immune link after birth, favors the transmission of immunological competence, and is considered an important contributing factor to the development of the babies' immune system. OBJECTIVE: This study aimed to obtain data related to the effects of gestational diabetes on immunoglobulin A (IgA) and cytokines levels in the colostrum, before and during the pandemic of the new coronavirus, in order to study the possible outcomes regarding the immunological characteristics of human milk. METHODS: This systematic review was registered in PROSPERO CRD42020212397, and the question elaborated using the PICO strategy was: does maternal hyperglycemia associated or not with Covid-19 influence the immunological composition of colostrum? Electronic searching and reference lists of published reports were used to identify studies that reported the influence of gestational diabetes on colostrum and milk composition. RESULTS: Seven studies were selected from the 51 found, six of them were cross-sectional and one was a case report. Six studies included Brazilian groups and only one was conducted in USA. The mothers with gestational diabetes presented a reduced level of IgA and other immunoreactive proteins in colostrum. Those alterations could be related to changes in macronutrient metabolism and cellular oxidative metabolism. CONCLUSION: It was possible to conclude that diabetes changes the immunological composition of breast milk; however, data on the impact of the association between gestational diabetes and Covid-19 infection on the composition of antibodies and cytokines present in human milk are still scarce and inconclusive.