Neonatal (Newborn) Weight Loss

Neonatal weight loss is another issue of concern to nurses and pediatricians. A weight loss of 5% in the first week of life is considered normal for the bottle fed infant. A loss of 7% is average in the first week for the breastfed infant, 10% is the absolute maximum (Lawrence and Lawrence 397-398). If the baby loses 7% in the first 72 hours, breastfeeding should be observed by a trained professional for proper technique and milk transfer. If the baby is nursing well, appears otherwise healthy, and has appropriate stooling patterns  another weight check should be scheduled in two days. See  Is baby getting enough?

Why Do Babies Lose Weight?

There are several theories about why neonates lose weight. The most common theory is that babies are born with extra weight to help with the stress caused by labor and the transition to extrauterine life. Also the extra fat stores are there because mother's mature milk does not come in for 3-5 days.

The use of I.V. fluids in labor causes a large shift of fluid from the mother to the fetus especially when D5W or Lactated Ringer's is used (Keppler). In cases of maternal gestational diabetes, IDDM, or women who have received large amounts of IV fluids in labor, it is important to be aware that the birth weight may be inflated by excessive fluid stores in the infant. The infant's initial weight loss may be greater than 10% maximum due to surplus fluid loss.

Additionally the use of dry heat from radiant warmers and isolettes (incubators) causes insensible fluid loss. Some infants are left to "bake" under radiant warmers or in isolettes for hours after birth, this causes fluid loss and makes the infant lethargic (sleepy). Infants fall asleep and will not suckle if the environmental temperature is above 80° F (Lawrence and Lawrence 238 ).


Giving babies water or formula during the neonatal period can also contribute to weight loss.

A study by Glover and Sandilands showed that "Unsupplemented babies lost significantly less weight than babies supplemented with 5% glucose water (165)."

Mother should be reassured that weight loss is normal and baby will be back to his birth weight between two and three weeks of age.


Mothers should be told the infant's hospital discharge weight.

If the weight loss is of concern, the baby should have a weight check between three and five days after hospital discharge. If all is well, the baby will have gained weight from hospital discharge weight.

Weight gain in a baby should always be calculated from the LOWEST known weight. Babies should always be weighed naked on the same scale at every pediatric visit. The health care provider should always balance the scale before weighing the baby. Weight gain is only one measurement of growth. Babies also should have length and head circumference measured at each pediatric visit.

Copyright Marie Davis, RN, IBCLC  1999 
Last Reviewed: Saturday, September 11, 2010

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