Does baby seem to be in any pain or uncomfortable in any way? Any blood? How’s his milk intake? Is he on formula milk? Formula milk babies tend to have black green stools. If all seems normal you can wait for a little bit.
for the first few days of life usually their poop is black to dark green. some can be black with a tar-like consistency too. but if you are uneasy about it go go go for checkup
The 1st 2 months the poop color is dark green to blackish because of the bile , consult ur doc on the same in ur next visit 🙂