my wife have 15 days old baby Boy but the growth of baby not show in his body. what can I do?

A. Intially newbies shed some weight. in the first 3 months, babies put on about 800-900grams each month. From 3-6 months, weight gain reduces to 1/2 kg/month. from 6-9 months, it becomes 1/3, and for 9-12 months, it becomes 1/4 kg. the birth weight doubles in the 4th month and triples when they reach 12 months of age.