Constipation is a very common problem during pregnancy. Constipation can be accompanied by hemorrhoids and anal fissures, making defecation very painful. Constipation is treated with a proper diet: food containing cellulose fibers such as fruits and vegetables are most helpful. If your body needs more fiber, you can take a water-soluble fiber supplement like psyllium husks or acacia. For a really troubled gastro-intestinal tract, moderate laxatives (dulcolax, liquid paraffin) are recommended. Strong laxatives (MgSO4, oleum ricini) are not recommended because the can cause contractions in the uterus. Bowel cleaning (enema or colonic) is a final possibility if the previous methods don’t help. It sounds as though you are bleeding from an anal fissure but your gynecologist will have to confirm this AND exclude vaginal bleeding. It is very important to maintain proper hygiene in the pelvic basin to prevent infections.