my baby birth weight is 2 .3 at 42 days her weight is 3.4 is this correct or need improvisation

A. Which child has gained 1100 g in 42 days where a minimum weight gain in a month should be around 500 g and maximum up to 1 KG if you look at the birth weight and the current weight gain in 42 days this is a very good weight gain for your child has