It is known that there are maternal-neonatal factors associated with the weight loss of newborns during their adaptation period. The objective of this research was to characterize the factors that influence the weight loss of term neonates, for which the non-experimental design of relational level was used and information on the maternal-neonatal characteristics of 60 newborns was recorded through documentary analysis. of a public hospital. The inferential statistics allowed determining that, from the maternal factors, the mother's disposition towards breastfeeding obtained a calculated value Xi2 = 4.494 (p = 0.034) and regarding the neonatal factors, the type of feeding obtained a calculated value Xi2 = 7.578 (p = 0.006), thus concluding that both the mother's disposition towards breastfeeding and the type of feeding were the factors that influenced the weight loss of the newborns.