Final answer:
Babies typically gain about 28 grams per day in the first two months and then about 0.45 kg per month thereafter. They usually double their birth weight by the sixth month and triple it by their first birthday.
Step-by-step explanation:
In the first couple of months, babies are expected to gain weight rapidly. Following an initial decrease in the first week after birth, a healthy neonate should typically gain about 28 g (1 oz) per day during the first two months. As the infant grows, the rate of weight gain will slow somewhat, and from the third month onward, the infant will likely gain about 0.45 kg (1 lb) per month. By around six months, a baby usually doubles its birth weight, and by twelve months, triples it. Regular checkups are essential to ensure that the baby's growth is on track and to address any concerns about undernourishment or potential obesity.