Newborn Weight Loss

I’ve lately taught a few classes and had a few discussions with people who have some misconceptions about newborn weight loss. I thought I’d take a minute to share what parents of exclusively breastfed babies can expect in the early days.

  • Most babies, regardless of feeding method, will lose some weight after birth. This is due to moving out of their aqueous environment, and passing the first stools (meconium). Exclusively breastfed babies lose approximately twice as much weight as bottle fed babies, and that is normal.
  • The average weight loss for an exclusively breastfed baby is approximately 5-7% of their birth weight.
  • Babies who are born by Cesarean Section, to mothers who receive IV fluids, who are a younger gestational age, who are larger birth weight, and who are girls may lose a bit more weight. However, any weight loss over 7% should still be evaluated (by an international board-certified lactation consultant–IBCLC).
  • A 10% weight loss–the number that is routinely thrown out there as normal–is a red flag that baby is not feeding well. At this point, the baby should be referred to both an IBCLC and a physician, and some sort of supplementation may be in order (either expressed breast milk or formula in most cases). Remember–Rule #1 (by the illustrious Linda Smith) is FEED THE BABY.
  • The lowest weight is generally seen between days 2-4. If the baby is still losing after day 4, feeding should be evaluated.
  • While diaper output is certainly a good indicator that feeding is going well, it is necessary to do a few weight checks to be certain.

Reference: Breastfeeding Answers Made Simple, by Nancy Mohrbacher, 2010