If a woman has black stool after pregnancy, the following factors should be considered: 1. Consider that the gastrointestinal tract peristalsis slows down during pregnancy, resulting in significant constipation. This is because the stool will accumulate in the intestinal tract for a long time, so after it is discharged, the color will be especially black. 2. Consider that the woman has a combination of gastrointestinal diseases in pregnancy, so it leads to a small amount of bleeding in the digestive tract, which causes the stool to be black, and then you will see a tar-like change in the stool. 3. Consider that the woman is taking iron supplementation drugs during pregnancy, such as glucosamine. This is because after taking these drugs, the metabolism will lead to a black stool change. A small number of women also have black stools after taking pig liver, black fungus, and blood fungus.