Hello doctor my baby boy birth weight 2.kg... now 4 month 10 days present baby weight 4.2 is it's normal

A. That’s very healthy because your child is gaining a minimum of 550 g in a month which is actually right kind of weight gain that the child should be having about 4 to 500 g in a month say child is gaining much better than that so whatever feeding you are giving is enough for the child