[Weight descent curves in term newborns during the first 48 post-natal hours, feed with exclusive breast milk]

The healthy newborn (NB) experiences physiological weight loss in her/his first days of life. Identi fying normal weight loss in this period is relevant since it allows the clinician to make decisions in relation to the need to supplement breastfeeding.

To determine the curves that graph the weight loss experienced by healthy newborns exclusively breastfed during the first 48 hours after birth.

Retrospective and analytical descriptive study in healthy full-term NBs during their stay in the nursery, exclusively breastfed, and with mixed feeding. Weights were recor ded at birth and on the first and second day of life. A quadratic polynomial was used to model the relative weights. The percentiles of the variations in weight loss were estimated.

The sample consists of 4331 NBs with an average gestational age of 38.84 weeks. Of these, 56.45% were vaginal deliveries and 43.55% cesarean sections. The distribution by sex was 49.37% male and 50.63% fema le. Regarding adequacy, 82.96% were adequate for gestational age, 6.33% were small for gestational age, and 10.71% were large for gestational age. The greatest weight loss was observed in the first 12 hours of life.

A weight loss graph is obtained for the first 48 hours of life, representing the weight loss per hour for healthy term NB exclusively breastfed. These curves can be used as a decision-making tool to categorize the weight loss of the NB and help in decision making regarding the indication to add artificial feeding.