Bowel habits frequently change during pregnancy, ranging from a significant slowdown to an unexpected increase in bathroom visits. These digestive shifts are highly variable and can occur at any point from the first trimester through the final weeks. While these changes are often uncomfortable, they are a normal physiological response to the profound transformation happening within the body.
Why Constipation is the Most Common Change
The most frequent bowel complaint during pregnancy is constipation, affecting between 16% and 50% of pregnant women. Constipation is defined as having fewer than three bowel movements per week, accompanied by hard, dry stools that are difficult to pass. This irregularity often begins early in the first trimester, coinciding with the initial surge of pregnancy hormones.
Increased bowel transit time means waste material remains in the large intestine for longer periods. This extended duration allows the colon to absorb more water from the stool, causing it to become firm and lumpy. Many women also report a feeling of incomplete emptying or a need to strain, which can lead to issues like hemorrhoids.
Addressing Increased Bowel Movements and Diarrhea
The opposite of constipation—an increase in bowel movements or diarrhea—is less common but occurs. Diarrhea is defined as three or more loose or watery stools within a 24-hour period. This increased frequency can be a response to sudden dietary adjustments, new food sensitivities, or the introduction of prenatal vitamins.
An increase in loose stools often appears late in the third trimester as the body begins its final preparations for labor. This digestive “clean-out” can happen in the days or hours before contractions begin, though it is not a definite sign that labor is immediate. It is important to differentiate between temporary, mild changes and persistent, severe diarrhea.
The Primary Drivers of Pregnancy-Related Bowel Shifts
The underlying cause for nearly all bowel changes is the elevated production of the hormone progesterone, which is essential for maintaining the pregnancy. Progesterone relaxes smooth muscles throughout the body, including the muscular walls of the intestines. This relaxation significantly slows down the rhythmic contractions, or peristalsis, that propel food and waste through the digestive tract.
This slowdown allows the body more time to absorb nutrients for the developing fetus, but it also increases bowel transit time, driving constipation. Later in pregnancy, the expanding uterus contributes a physical constraint to the system. The growing uterus crowds the abdominal cavity and exerts pressure on the lower intestines, impeding the passage of waste.
Another major contributing factor is the iron content in many prenatal supplements, which are prescribed to prevent or treat anemia. Iron is notorious for causing gastrointestinal side effects, specifically by hardening stools and making them difficult to pass. The body also increases its water absorption from the intestines, which is compounded by the slower movement of waste, leading to drier, tougher stools.
Safe Home Management for Bowel Irregularities
Managing bowel irregularities involves simple, consistent lifestyle adjustments focused on diet and hydration. For constipation, increasing dietary fiber intake to the recommended 25 to 30 grams daily helps add bulk to the stool, making it softer and easier to move. Excellent sources include whole grains, beans, fresh fruits, and leafy vegetables.
Adequate fluid intake is equally important, especially when increasing fiber, aiming for 10 to 12 cups of water or other non-caffeinated fluids daily. Gentle, moderate physical activity, such as a 20-to-30-minute walk several times a week, can also help stimulate gut motility. If these measures are insufficient, over-the-counter options like bulk-forming fiber supplements or stool softeners are considered safe, but any medication should first be discussed with a healthcare provider.
For managing increased frequency or mild diarrhea, the focus shifts to maintaining hydration and consuming bland foods. Drinking water, clear broths, and electrolyte-rich beverages is necessary to replace lost fluids and minerals. A gentle diet, such as the BRAT diet components (bananas, rice, applesauce, and toast), can help bind the stool. Avoiding foods that can trigger or worsen diarrhea, like excessively fatty, spicy, or high-sugar items, is beneficial for calming the digestive system.
When to Seek Medical Advice
While most bowel changes during pregnancy are temporary and manageable, certain symptoms require immediate medical attention. Persistent or severe diarrhea lasting longer than 48 hours is a concern because it increases the risk of dehydration, which can affect the pregnancy. Any instance of passing bloody stools, whether bright red or black and tarry, necessitates a prompt call to a healthcare provider.
Other red flags include experiencing severe, sharp abdominal pain or cramping not relieved by passing gas or having a bowel movement. Constipation that fails to improve after a week of consistent home management and lifestyle changes should also be discussed with a doctor. These symptoms may indicate an underlying issue requiring professional assessment and intervention.