How much weight loss is too much? Establishing evidence-based guidelines for neonatal weight loss

Background: There is no one standard for normal newborn weight loss; guidelines differ by and within medical organizations. Cut-offs for acceptable weight loss range from 7-10% and fail to acknowledge potential differences due to birth factors and newborn feeding.

Objective: To determine normal neonatal weight loss

Design/Methods: Using a prospective cohort design, 76 infants born at an urban Boston hospital were weighed daily for the first week of life. Infant weight was obtained from the medical record, and from home visits post-discharge. All feeds in week 1 of life were recorded, from the bedside feeding chart and a food diary completed by the mother. Birth-related factors which may affect weight loss were abstracted from the medical record.

Results: Mean weight loss was 4.8% (range 0.00%-9.9%). 21.1% (16/76) of infants lost >7% of their birthweight, although no infant lost >10%. Maximum percent weight loss was significantly associated with feeding (p=0.00): Exclusively breastfed infants lost 5.8%, mainly breastfed infants lost 5.3%, mainly formula fed infants lost 2.9% and exclusively formula fed infants lost 1.2%. When feeding category was collapsed into exclusively or mainly breastfed (n=61) and exclusively or mainly formula fed (n=15) type of delivery, parity, gestational age, race, insurance, WIC benefits, and infant gender were not associated with percent weight loss. Maternal place of birth was significantly related to weight loss (p=0.03), although place of birth was strongly associated with infant feeding.

Conclusion: Infants who consumed more formula lost less weight. Type of delivery did not affect weight loss nadir.