my son is 13 months old, from last 4 months his weight is 8 kg. his birth weight was 3.200 . pls dr tell me wt can I do to improve his weight ?

A. hi dear Most babies double their birth weight by five to six months of age and triple it by the time they are a year old. By one year, the average weight of a baby girl is approximately 19 pounds 10 ounces (8.9 kg), with boys weighing about 21 pounds 3 ounces (9.6 kg).