Blackish Poop and Constipation

Mga Mommies, ask ko lang po kung yung poop nyo po ba during pregnancy is color black and super tigas :c medyo bothered po ako baka may mali or ano. I'm taking Folic Acid, ObvitMax, Calcium and Ferrous daily tsaka EnfaMama every night. Normal lang po ba or should I consult my Ob na agad? para kasi akong nanganganak everytime na popoop ako sobrang hirap :c Thanks po sa sasagot!