My baby weigt just only 4kg in 2.5 month? Is it normal?

A. Hai good afternoon !! Baby's birth weight?? Generally babies increase 400-800 gm per month, doubles their birth weight by 5-6 months. Check if baby increasing on an average 400-800 gm per month ... According to age baby weight is ok but still have to check with birth weight... ;Give exclusive breast milk or formula milk until 5 complete months...