my baby is one month old now. he is on breastfeed he is not increased his weight from last 3 days what should I do?

A. hello in the first month you cannot expect much weight gain and baby weight will reduce in the first month and then baby starts gaining and if baby is gaining a minimum of 150 grams to 200vgrams per week then it is a good weight gain and if bm is not sufficient then give baby infant formula milk stage 1 using a bpa free bottle like Babyhug