A baby in hot weather needs water, just like adults

The American Academy of Pediatrics (AAP) is categorical: babies under 6 months should not be given water. Breast milk and infant formula are composed mostly of water and fully cover fluid needs, even in very hot climates. This is not an opinion, but the unanimous position of paediatric organisations.

The reason is physiological: a newborn's kidneys cannot yet handle an extra water load, and the stomach is the size of a walnut. Every sip of water takes the place of a sip of milk, and with it, of calories and nutrients.

Offering water to a small baby carries two real risks. The first is electrolyte imbalance: excess water dilutes sodium in the blood and in severe cases leads to so-called water intoxication, a condition requiring emergency care. The second risk is nutritional: the baby fills up on water, suckles less and receives less food exactly when it is growing fastest.

The same logic applies to diluting formula with more water than stated on the package. This is not a harmless hot-weather trick, but a direct reduction of the meal's nutritional value.

The right answer to heat for a breastfed baby is offering the breast more often, even for short feeds. The foremilk at the start of every feed is more watery and it is exactly what quenches the baby's thirst. For a baby on infant formula, offer the usual dose more often, without diluting it.

Watch the real signs of adequate hydration: 6-8 wet nappies per day, light-coloured urine, an awake and active baby. Warning signs are rare and dark urination, dry lips, crying without tears and a sunken fontanelle. With these, seek a paediatrician immediately, not a bottle of water.

With the introduction of solid foods around 6 months, small amounts of water begin too: a few sips with meals, up to about 120-240 ml per day. The goal at this stage is not so much hydration as getting used to the taste of water and drinking from a cup.

Our verdict: the claim is a MYTH. In hot weather, a baby under 6 months is hydrated with more milk, not water. Water enters the menu after 6 months, gradually and in small amounts, and with any suspicion of dehydration the paediatrician is the person you call first.

The information in this article has been verified and is based on: the American Academy of Pediatrics hydration recommendations for babies (healthychildren.org), including the position that breast milk and formula provide adequate fluids even in hot climates, and the US Dietary Guidelines for exclusive breastfeeding during the first 6 months.