Water and sugar water (glucose water) should not be used as supplements for newborn babies. This is an old practice and is no longer recommended.
There is no evidence of benefit to newborns from the brief use of additional water or glucose water and it may reduce the duration of breastfeeding (Becker 2014). The Academy of Breastfeeding Medicine states that (Kellams 2017):
“Supplementation with glucose water is not appropriate because it does not provide sufficient nutrition, does not reduce jaundice, and may cause low sodium levels in the blood (hyponatremia)."
If a newborn baby requires a supplement, it should be appropriate milk.
One large survey reported that 4.2% of U.S. hospitals surveyed in 2013 gave water to babies and 12% gave glucose water to babies (Nelson 2016).
Glucose water is different from glucose gel, a form of medicine used to treat babies with low blood sugar.