A breastfed newborn doesn't need any supplemental water; breast milk supplies all the hydration he needs. Water can fill your baby up and cause him to nurse less frequently, which leads to reduced calorie intake and a decreased milk supply. Feeding your newborn supplemental water can also have more potentially serious side effects.
Newborns do need fluid, but breast milk contains plenty. Breast milk is 88 percent water, certified lactation consultant Kelly Bonyata explains on her website, KellyMom. All babies lose up to 7 percent of their body weight and regain it within the first 10 days of life, according to the American Academy of Pediatrics; early weight loss is not a reason for supplementation. Giving supplemental water increases, not decreases, initial weight loss, pediatrician Dr. Jay Gordon cautions.
Supplemental Water and Establishing Milk Supply
Giving your baby supplemental water can sabotage your breastfeeding efforts. Breast milk production works on a supply and demand principal; when you give your baby water, he's less thirsty and nurses less. Because he nurses less often or less vigorously, your milk supply can dwindle before it even gets well established. For this reason, the American Academy of Pediatrics recommends that hospitals should not offer supplemental water to infants unless the physician specifically orders it.
Supplemental Water and Jaundice
Hospital staff might suggest that you give your breastfed baby supplemental water if he develops physiological jaundice, as around 60 percent of newborns do, according to a 2007 article published in "Paediatric Child Health." But supplemental water or water with dextrose doesn't improve or prevent newborn jaundice, according to Gordon. In fact, bilirubin levels may rise higher in breastfed babies given supplemental water than in those who don't receive supplementation, lactation consultant Anne Smith warns.
Supplemental Water in Hot Weather
Even when it's very hot outside, your newborn baby doesn't need extra water, as long as he's nursing frequently. You, however, should make sure you drink enough to produce an adequate supply of breast milk. Once your baby reaches the age of 6 months, you can give supplemental water in small amounts, but he still doesn't need water in his first year, Gordon states.