Black stool in pregnancy: what to know

Iron tablets commonly make bowel movements dark green, brown, or black. Some strongly coloured foods can do the same. Stool that is jet black, sticky, shiny, and tar-like is different: it can contain digested blood from the stomach or upper intestine. Conditions such as Gastritis, Helicobacter Pylori Infection, and Peptic Ulcer can irritate or damage the lining there. Pregnancy itself does not make tarry stool something to ignore.

Note whether the change began after a new supplement, how often it occurs, and whether the stool is formed or sticky. Abdominal pain, nausea, unusual tiredness, dizziness, or vomiting blood adds concern.

Check the label of every supplement, including prenatal iron, and make a note of recent foods and medicines. Do not stop prescribed iron or start a treatment on your own; contact your maternity team or clinician for advice. They may ask about the appearance of the stool and arrange blood tests or stool testing, depending on your symptoms. Keep drinking fluids unless a clinician has restricted them.

Seek urgent medical help if the stool is tarry or repeatedly black, or if you feel faint, confused, breathless, very weak, or have a fast heartbeat. Urgent assessment is also needed for severe abdominal pain, vomiting blood or material that looks like coffee grounds, or heavier bleeding. During pregnancy, tell the maternity service about any collapse, reduced fetal movement, or other pregnancy concern while arranging care.

Could my prenatal iron explain this colour? Does the stool look like digested blood? Do I need a blood count or examination? Which pain medicines and supplements should I avoid? What symptoms mean I should attend emergency care?