my son is 48 days old but when born his weight is 3.7 kg but now his weight not gaining

A. It should be at least 4.7 by completing the age of two months if your child is not even gaining 500 g in a month minimum which is a major requirement then your child is not gaining from your feet then in that case I would recommend you that you should proceed with formula Mail for your child which is what is going to be good