Fruit of the Womb
Fruit of the Womb

Constipation in Pregnancy

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A writer recently requested some information regarding "constipation in pregnancy." Having just gotten over the consequences of my Norovirus infection, I thought I might welcome a little constipation in my life, even if it isn't one of our more 'moving' topics (sorry, I couldn't help myself). Regardless, here are my responses to her questions...

What are some causes of constipation during pregnancy?
One of the primary causes of constipation in pregnancy is the hormone progesterone. Progesterone is the hormone that dominates the second half of a woman’s menstrual cycle after she ovulates. It is made early in the pregnancy by persistence of the site on the ovary (the corpus luteum) from which the egg that made the baby is produced. By the end of the first trimester, the placenta takes over production of large amounts of progesterone. One of the major effects of progesterone is to cause relaxation of ‘smooth muscles.’ Organs that contain smooth muscle are the blood vessels, the uterus, and the bowel. Progesterone decreases the strength and the frequency of bowel contractions that are necessary to move food, fluids, and wastes through the bowel. The slower the motility of the bowel, the greater the opportunity for absorption of fluid and foods. Unfortunately, by the end, if the remaining waste becomes very dehydrated, the stool becomes compact and hard, making it more uncomfortable to pass, sometimes getting to the point where a woman will not have a bowel movement for 5 or more days. This is constipation and it can be very uncomfortable. Other causes are iron and calcium supplements, poor fluid and fiber intake, and too little exercise during pregnancy.

How common is it?
More than 50% of all pregnant women suffer some degree of constipation. It is probably only second to headaches among common pregnancy complaints. Think of it as ‘nature’s way’ of getting the mother to absorb the most food and fluid from her diet she possibly can to help nourish her baby and maintain the pregnancy - at a cost!

When does it typically occur? How long can it last?
It can begin early in the first trimester, but usually becomes more of a problem only from 20 weeks on when, not only are there high progesterone levels, but the uterus enlarges to the point that it can impede movement through the bowel by its sheer size and position in the pelvis. Some people are unusually prone to constipation because of poor fluid or fiber intake in their diets, so it can be a chronic problem throughout the pregnancy.

What are some ways to prevent this?
Drink plenty of fluids (8-12 glasses per day); take in plenty of fiber – 15 grams or more per day (fruits, vegetables, whole grains, beans);and, although iron and calcium are important minerals for both mothers and their babies, they can both worsen constipation. Get some exercise (unless you have a reason to be at bedrest). This will improve bowel motility.

How can it be treated? Fluids, fiber, bulk laxatives (such as Metamucil and Citrucil). Avoid irritant laxatives, mineral oils, and irritating enemas since these might also cause the uterus to contract prematurely. Add some daily, non-jarring exercise to your routine.

When is there cause for concern?
If you haven't had a bowel movement in 4-5 days, you should notify your provider of your dilemma. When the stool becomes very hard and distends the bowel, then pain and bleeding can occur. This can be a serious problem if a woman has large hemorrhoids (enlarged veins in the rectum and anus) which could tear and bleed quite heavily. Also, when the bowel gets over-distended or ‘impacted’ in its lowest portion, it can release chemicals that try to force the bowel to contract. These same chemicals, in close proximity to the uterus can make the smooth muscle of the uterus also contract and actually precipitate premature labor!
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About the Author

Dr. Trofatter is an expert on maternal-fetal medicine.

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