My 1 month year old baby is having constipation what should I do?

Breast or formula ? Breast fed infants can go a little every feed or overflow a diaper once a week. If it is soft when they go i don't worry about it. Formula fed babies usually have a more predictable pattern of daily stools. If stools are getting hard, i often try full strength prune juice, 1oz once or more/d.Takes about 3d to get things moving.
Not constipated? It would be very rare for a child this age to have constipation since they are only taking in formula or breast milk. It is perfectly normal, for example, for breastfed infants to have a bowel movement once a week. Formula-fed go more often. How often does your baby go? If your baby is feeding well and not vomiting, you baby is ok.