my son is 7 months old and weighs 8.5 kg... he weighed the same at 6 months. he didn't gain weight in a month. his birth weight was 3.8 kg..he doubled his birth weight at around 4.5 months. but between the 6th and the 7th month he didn't gain any weight. he is overall very active. if this trend continues how will he triple his birth weight by 12 months..is it necessary to triple the birth weight by 12 months.