Hi doc. My son is 9 month old but his weight is only 7 kg he isn't gaining his weight what do i do for that

A. hi dear While all babies may grow at a different rate, the following is the average for boys and girls 7 to 9 months of age: Weight: average gain of 1 pound each month; boys usually weigh about ½ pound more than girls; 2 times the birth weight by 4 to 5 months and 3 times the birth weight by 1 year.