Hi
Most common cause of black stool in pregnancy is iron tablets. Most doctors inform patients about the symptoms when they start iron tablets. Black stools are problematic if you get dizzy or have drop in hemoglobin and stools are very foul smelling.
The main issue for you is to determine whether it is true bleeding or related to iron therapy
Next Steps
You can discuss your case with me.
I need the doctor prescription who have started you on heparin and what was the indication.
FOBT test done or not since the symptoms can help
Health Tips
You can upload you Recent hemogram report