Infants and Toddlers Babies and toddlers are growing and developing rapidly during the first few years of life. A child’s brain is 80% of its adult size by the time he or she is just two years old. Good nutrition is paramount. There are no right or wrong answers though and each baby is different. Offer your baby a wide variety of foods but don’t worry if they dislike or reject some – that’s only natural. It often takes several attempts before new foods are enjoyed.