Baby’s Weight

From Breastfeeding Made Simple by Mohrbacher and Kendall-Tackett, 2010:

As we said before, newborns (breastfed and bottlefed) typically lose weight during the first few days after birth while they shed their excess fluids.

In a 1991 study, Sandra DeMarzo and her colleagues found that when mothers received good breastfeeding guidance and support, babies lost no more than 7% of their birth weight during these first 3-4 days. A weight loss of up to 10% is considered in the normal range, but if your baby has lost 7-10% of birth weight, it may be time to take a closer look at breastfeeding to make sure baby is feeding well; some adjustments may be needed.

NOTE: Babies should reach their low weight by four days of age. If a baby is still losing weight after 4 days, seek skilled breastfeeding help immediately.

Even if a baby’s diaper output is within the normal range, a weight check is suggested. The American Academy of Pediatrics recommends that every newborn be seen by her doctor at 3-5 days of age. If a baby has few-than-expected wet diapers and stools, it’s important to know that the baby scales available at most baby stores are not accurate enough to rely on during this time.

Neither is the strategy that occurs first to many new parents, which is to get on the bathroom scale alone, then with the baby, and subtract the first weight from the second.

Instead, a doctor’s or lactation consultant’s scale should be used to check the baby’s weight and the baby should be naked (no diaper) when weighed.

Most scales used by board-certified lactation consultants are accurate to either 0.1 oz. or 0.35 oz., and some doctors provide free weight checks for their patients.