Kerin writes: "I know it's important to stay hydrated in the hot summer months. My older kids carry water bottles on outings, but what about my 5-month-old? Should I give her water, too?"

During the summer, your baby needs to stay well-hydrated too, but don't give her water or water down her formula, even on the hottest days. During the first year of life, breast milk or formula is all she should have.

In fact, giving infants water can be dangerous because they can easily suffer from water intoxication, a condition in which their developing kidneys can't excrete water fast enough. As a result, water builds up in the body and dilutes the electrolyte balance of the blood, which can cause seizures, coma, or even death.

If you sense your baby's thirsty, give her a little extra breast milk or formula (mixed according to manufacturer's directions) instead of water.

See our report on baby bottles and nipples and breast pumps for more information.