Coffee-colored stuff flowing underneath one month of pregnancy may be a preterm miscarriage, ectopic pregnancy and indolent miscarriage, the specific causes and treatment methods are as follows: 1. Preterm miscarriage: Preterm miscarriage caused by low progesterone may appear with coffee-colored material flowing out of the vagina. If the progesterone is lower than 24mmol/L, it is necessary to take progesterone tablets, vitamin E and birth control pills under the guidance of a doctor. 2. Ectopic pregnancy: the fertilized egg is laid outside the uterine cavity and the pregnancy tissue ruptures and bleeds, which can be manifested as coffee-colored material flowing out. In this case, it is necessary to go to the hospital immediately for examination and symptomatic treatment after diagnosis. For example, early ectopic pregnancy can be treated with mifepristone and misoprostol, but if it is more serious, with more bleeding or more severe stomach pain, surgery is needed in time; 3, indolent miscarriage: also known as fetal abortion, the fetus dies for several days or weeks and remains in the uterine cavity without being expelled naturally, which will manifest as vaginal outflow of coffee-colored material. If the diagnosis is confirmed, surgery should be performed as soon as possible.