Hidden pain in the abdomen with brown discharge in late pregnancy may be a symptom of preterm labor, but it is not absolute, hidden pain in the abdomen and brown discharge can also be caused by two different reasons. The vague pain in the abdomen in late pregnancy may be a true uterine contraction, which is a precursor to labor. At first, the uterine contractions are weak, with a relatively short duration of about 30 seconds and a longer interval of about 5-6 minutes, and will be characterized by vague pain in the abdomen. As labor progresses, the intensity of contractions gradually increases, the duration is gradually extended, the interval is gradually shortened, and the pain gradually increases, which is a sign of impending labor, so be prepared for labor. Brown discharge in late pregnancy may be red, is the fetal membrane and the uterine wall at the place of stripping, there are small capillary rupture caused by bleeding, is also a sign of labor, be ready to wait for labor. Excluding the above precursor to labor, late pregnancy abdominal pain may also be caused by ligament pulling in the process of uterine enlargement, brown discharge may be caused by gynecological inflammation, such as cervicitis pregnant women, inflammation stimulates the mucous membrane congestion, edema, there will be brown discharge. There are more reasons for brown discharge in late pregnancy with vague pain in the abdomen, and it is recommended to consult a doctor for examination in a timely manner if there is any abnormality.