Black-coloured stool during pregnancy

Iron-containing prenatal vitamins commonly make bowel movements darker. Dark foods and bismuth-containing products can also alter colour. A bleeding stool is more likely to look black and tar-like, with a sticky or shiny surface and an unusually strong smell. Gastritis, Helicobacter pylori infection, and peptic ulcer can affect the stomach or nearby intestine and may present with black stool. The colour alone cannot separate these causes.

Review your prenatal vitamins and other products, but do not stop prescribed treatment without speaking with your maternity team. Note the stool’s texture, when it appeared, and whether there is pain, nausea, vomiting, weakness, or dizziness. Call your obstetric clinician or doctor promptly when the stool is tarry, persists, or has no clear link to something you took or ate.

Get urgent medical help for black stool alongside faintness, severe weakness, confusion, breathlessness, severe abdominal pain, blood in vomit, or coffee-ground vomit. Pregnancy can make sudden illness harder to judge at home, so contact your maternity service if you feel significantly unwell even before all warning signs appear.

Ask whether your iron dose or another product could explain the change, whether the appearance warrants testing, and which treatments are suitable in pregnancy. Provide the names of supplements, medicines, and remedies, including products bought without a prescription.