Percentage of birth weight loss as a reference for the well-being of the exclusively breastfed newborn

Abstract

As health professionals, we have memorized that "newborns can lose up to 10% of their birth weight during the first week of life and should regain it by two weeks of age". However, this statement, which appears so accurate, comes from studies conducted in the 1960s, when medical knowledge and how newborns were fed were utterly different from what it is today. Currently, multiple factors contribute to the percentage of weight loss at birth and the rate at which this weight is regained. There are nomograms for exclusively breastfed and formula-fed newborns and those by vaginal or cesarean delivery. To meet the World Health Organization's goal of exclusively breastfeeding newborns, it is essential to recognize that "loss of more than 10% of birth weight" does not represent the need for formula supplementation. When assessing these cases, we must consider several factors that influence the percentage of weight loss in newborns. Therefore, diagnostic decisions should always be individualized in favor of breastfeeding.

Personalised metabolic whole-body models for newborns and infants predict growth and biomarkers of inherited metabolic diseases

“…Loss of birth weight up to 10% in the first few days of life is normal, 45 and presumingly, due to fluid loss through urination. 46 It is to be noted that we did not change any water-related constraints in the personalised infant-WBMs. Unfortunately, no further information on the infants' follow-up weight (e.g., on day 3), general health status (besides the tested IMDs), potential feeding problems, delivery mode, or the age of the mother where available, to validate the predicted loss in weight.…”