A newborn’s nutritional needs are fulfilled by human milk only. In the initial 2-3 days, the mother’s milk contains colostrum which is enough for the baby even if produced in small quantities; this is because the capacity of the baby’s stomach is small too (5-7ml only).
Then, as the colostrum is replaced by mature human milk, the milk production increases as per the increasing capacity of the baby’s stomach. Mother’s milk can fulfill all the nutritional needs of the baby until 6 months of age. Hence, exclusive breastfeeding is recommended for up to 6 months of age.