Thereafter, rapid growth occurs with most infants doubling their birth weight by 4 months and tripling it by 12 months of age. Hydration is crucial for infants. Dehydration can occur quickly in heat or with diarrhea or vomiting.
Water intoxication can occur if young infants are given too much plain water.
Iron-fortified infant rice cereal is usually introduced first as it is hypoallergenic, provides needed iron, and can be altered in consistency as the infant adjusts from liquid to thicker textures. Foods should be added to the diet one at a time with several days in between introduction of each food. This will allow time to observe food tolerance and screen for allergic symptoms. First foods should be the least allergenic, easiest to digest, and thinnest texture. As food tolerance becomes established, foods are advanced until by age one year the baby is meeting most of its nutrient needs from table-foods.