The most common cause of bleeding in the stool is hemorrhoids, which may lead to the appearance of hemorrhoids or aggravation of the original hemorrhoid symptoms due to the growing fetus and the gradual increase in abdominal pressure. 2. The presence of blood in the stool during the second month of pregnancy may be caused by anal fissure, which is usually accompanied by obvious constipation, and the pain is particularly severe when defecating. The actual pain is particularly intense and unbearable when defecating. 3, the blood in the stool in the second month of pregnancy may be due to ulcerative colitis. If you find blood in your stool in the second month of pregnancy, it is advisable to go to a regular specialist hospital for systematic examination and clear diagnosis, then according to the different causes of timely symptomatic treatment, and at the same time in the treatment to choose some drugs that have little impact on the fetus.