Final answer:
Infants typically gain an average of 28 g (1 oz) per day during the first two months, and then gain about 0.45 kg (1 lb) per month for the rest of the first year.
Step-by-step explanation:
During the first two months, an infant typically gains an average of about 28 g (1 oz) per day. After that, weight gain slows down and the infant usually gains about 0.45 kg (1 lb) per month for the remainder of the first year.
By the end of the first 6 months, an infant generally doubles its birth weight, and by 12 months, it triples its birth weight. Additionally, during the first six months, infants grow about 2.5 cm (1.0 in.) per month in overall body length.