Newborn Weight Loss Calculator

Yes, it is entirely normal. Newborns lose weight because they pass meconium (first stool), lose excess fluid accumulated during birth, and may take 2–3 days to establish a good feeding rhythm. This physiological weight loss is expected and does not indicate a problem in most cases.

The AAP considers up to 7% of birth weight to be normal in the first week. A loss of 7–10% warrants close monitoring and increased feeding. Anything greater than 10% requires prompt evaluation by a pediatrician, as it may indicate inadequate feeding, dehydration, or an underlying medical issue.

Most healthy newborns return to their birth weight by 10–14 days of age. Formula-fed babies often regain weight slightly faster (by 10 days) than breastfed babies (by 14 days). If your baby has not regained birth weight by 2 weeks, contact your pediatrician.

Yes. Breastfed babies tend to lose slightly more weight in the first few days (median around 6.6%) compared to formula-fed babies (median around 3.5%). Both groups are expected to regain birth weight within 2 weeks. Colostrum transitions to mature milk around day 3–5, which often accelerates regain in breastfed babies.

Common causes include poor milk transfer (latch issues), low milk supply, delayed milk coming in, sleepy or jaundiced baby who is not feeding effectively, or less commonly, a medical condition affecting feeding or absorption. A pediatrician or lactation consultant can help identify the cause.