Why would my 3 week old breastfed baby be constipated?

Not getting : Enough breast milk is a factor. Can you please describe your baby 'a stools and frequency? Breast milk is easily digested and some babies may not have bowel movements for one week!

Feeding: May not be getting enough milk. Adequately fed breast fed babies tend to HAV egood bms.

Depends: Straining or irregular stooling doen not mean constipation.The nb breast fed kid may go 7-10 days without a stool or poo a little at each meal.As long as it is soft, i don't consider that constipation. If the kid is putting out dry rabbit pellets or stool bigger than your finger you can sometimes tease a stool out using vasaline on a q-tip inserted to the length of the cotton & worked around.