Key takeaways: Most newborns lose some weight in the first days, usually less than 7 to 10 percent of birth weight. Most regain birth weight by 10 to 14 days. Larger losses mean your baby’s feeding needs a closer look. Weight checks after discharge are important.
Hearing that your baby has lost weight can be alarming. But early weight loss is expected. What matters is how much, and how quickly your baby starts to gain.
Why Babies Lose Weight
- Fluid loss: babies are born with extra fluid, which they lose through urine, stool, and breathing.
- Meconium: passing the first stools.
- Small early feeds: colostrum comes in small amounts, matching a newborn’s small stomach, before milk volume increases.
How Much Is Normal?
Most exclusively breastfed babies lose less than 7 to 10 percent of their birth weight, with the lowest weight usually around days 3 to 4. Formula-fed babies often lose a little less. Babies born by cesarean may lose a bit more, possibly related to IV fluids during labor.
Researchers have created newborn weight loss charts (nomograms), such as the Newborn Weight Tool (NEWT), that compare a baby’s weight loss by hours of age and delivery type. Many hospitals use them to identify babies who need extra feeding support.
When Do Babies Regain Birth Weight?
Most healthy babies are back to birth weight by 10 to 14 days. After that, typical gain is roughly two-thirds of an ounce to one ounce (about 20 to 30 grams) per day in the first few months.
When Weight Loss Needs Attention
- Weight loss of 10 percent or more.
- Weight loss that continues after day 4 or 5.
- Not back to birth weight by about 2 weeks.
These signs mean your baby’s feeding should be evaluated. Often, help with latch, more frequent feeds, and sometimes temporary supplementation solve the problem.
Signs Feeding Is Going Well
- At least 8 to 12 feeds in 24 hours.
- Wet diapers increasing each day, reaching 6 or more by day 5 or 6.
- Stools changing from black to yellow by about day 4 or 5.
- Audible swallowing during feeds.
Weight Checks
Your baby’s first outpatient checkup is usually at 3 to 5 days old. If your baby lost a lot of weight or feeding is challenging, your doctor may schedule extra weight checks.
Call your baby’s doctor if your baby: has fewer wet or dirty diapers than expected, still has dark stools after day 5, is very sleepy and hard to wake for feeds, looks increasingly yellow, or seems to be feeding poorly.
The Bottom Line
Some newborn weight loss is normal. Most babies lose less than 7 to 10 percent and regain birth weight by 2 weeks. Larger losses are a sign to get feeding help early.
Want more support for your baby’s first year? My book, From First Breath to First Birthday, is available on Amazon.
Sources
- Flaherman VJ, Schaefer EW, Kuzniewicz MW, Li SX, Walsh EM, Paul IM. Early weight loss nomograms for exclusively breastfed newborns. Pediatrics. 2015;135(1):e16-e23.
- Paul IM, Schaefer EW, Miller JR, et al. Weight change nomograms for the first month after birth. Pediatrics. 2016;138(6):e20162625.
- Kellams A, Harrel C, Omage S, Gregory C, Rosen-Carole C; Academy of Breastfeeding Medicine. ABM Clinical Protocol #3: Supplementary feedings in the healthy term breastfed neonate, revised 2017. Breastfeed Med. 2017;12(4):188-198.
- Noel-Weiss J, Courant G, Woodend AK. Physiological weight loss in the breastfed neonate: a systematic review. Open Med. 2008;2(4):e99-e110.
- Newborn Weight Tool (NEWT). https://www.newbornweight.org
This article is for general education and is not a substitute for individualized medical advice. Always talk with your baby’s health care provider or your own provider about your specific situation. If you think your baby or you may have a medical emergency, call 911.
