According to F. Gary Cunningham, M.D., chair of obstetrics and gynecology at University of Texas Southwestern Medical Center, 40 percent of women suffer from constipation at some point during pregnancy. Motility studies in pregnant women demonstrate that intestinal transit times increase progressively in each trimester of pregnancy. This delayed transit produces small, hard, pellet-like stools that tend to accumulate in the lower part of the colon, causing abdominal pain. Severe, localized, constant or persistent abdominal pain should be evaluated by a doctor in order to rule out more serious problems.
As for nonpregnant people, abdominal pain from constipation results from distention of the colon and rectum by trapped gases and stool. Since the nerves that supply the colon enter the spinal cord at the same levels as the nerves that supply the muscles and skin of the abdomen, patients "feel" colon pain as nonspecific abdominal pain.
Patients with abdominal pain caused by constipation typically describe it as mild-to-moderate, diffuse, crampy, episodic pain. In severe cases, constipation can cause pain that seems to radiate to the back. Pregnancy doesn't change the characteristics of constipation pain, so pain that seems different from usual constipation pain should be evaluated by a doctor.
The Mayo Clinic reports that most oral, over-the-counter laxatives are considered safe for pregnant women, although it's also important to read and follow package directions. For pregnant women in need of faster relief from abdominal pain than the six to eight hours required for oral medications, bisacodyl, a generic over-the-counter medication, can safely produce relief in as little as five minutes for patients who take the drug in enema form and 30 to 60 minutes for patients who take the drug as a suppository. If laxatives don't work on the first dose, pregnant women should contact their doctors for advice before taking further action.
Most patients prefer to prevent constipation before it arises. According to the American Dietetic Association, gradually increasing fiber intake in the form of over-the-counter fiber supplements; dietary intake of whole grains, legumes, fruits and vegetables; or both can help. Soluble fiber binds water, making stools softer, while insoluble fiber adds bulk and speeds transit through the gastrointestinal tract.
Constipation can result in complications such as fecal impaction, irreversible distention of the colon (known as megacolon), hemorrhoids and cracks in the tissue of the anus called fissures. Pregnant women face greater risks of constipation-related complications because of increased abdominal pressure caused by the enlarging uterus, distention of the veins in the colon and rectum caused by obstruction of blood flow below the uterus and hormones that reduce muscular contractions within the intestine.