Constipation is common in pregnancy for several reasons, including: 

• Hormone changes. An increase in the hormone progesterone during pregnancy slows the digestive process.
• Iron supplements. Often given to prevent anemia in pregnancy, iron supplements can make constipation worse.
• Changes in digestion. Your colon absorbs more water during pregnancy, which makes less water available for stool, resulting in harder stool.

Some tips for managing constipation during pregnancy include the following:

• Eat on a regular schedule. Small, frequent meals can help ward off constipation.
• Drink plenty of fluids, especially water. Aim for eight 8-ounces glasses a day.
• Exercise every day. Simple activities, such as daily walks, can be effective.
• Eat high-fiber foods, such as fruits, vegetables, beans and whole grains.
• Try fiber supplements, such as psyllium powder, Metamucil or Citrucel.
• If iron supplements are contributing to constipation, your doctor may adjust your dosage.
• A simple stool softener is safe to take in any trimester in pregnancy. But don't take any other type of laxative without first discussing it with your doctor.

• Stool softeners (Colace, Surfak, others) add moisture to stool, which makes stool easier to pass. The active ingredients in these products aren't absorbed by the body, so they're unlikely to have an adverse effect on the fetus.