Constipation during pregnancy: What your gut microbiome and hormones have to do with it

Pregnancy changes your body in ways no one fully prepares you for, and digestion is often one of the first surprises. Suddenly, something as basic as going to the bathroom feels different, harder, or just… off. If you’ve found yourself wondering whether constipation is “normal” during pregnancy, the answer is yes, and you’re far from alone.

According to the National Institutes of Health (NIH), constipation is one of the most common gastrointestinal symptoms during pregnancy and can begin as early as the first trimester. Still, many new and expecting moms hesitate to bring it up, brushing it aside as something minor or uncomfortable to talk about.

To help explain why constipation happens so often during pregnancy, and what’s actually going on inside your body, we spoke with Dr. Charles M. Carlsen, an obstetrician-gynecologist with over 20 years of experience caring for pregnant patients and the Founder of Drsono. His focus is helping patients understand pregnancy changes in a way that feels calm, clear, and empowering, not alarming.

Why constipation shows up so often in pregnancy?

“I am an OB-GYN, and I have practiced for over 20 years. I take care of pregnant women. Dealing with constipation is often the biggest complaint I hear. Patients often find it embarrassing to report. It does have effects on everyday activities and sleep,” says Dr. Carlsen.

The National Institutes of Health (NIH) identifies constipation during pregnancy as one of the most common digestive concerns, affecting many expectant mothers. While it’s often brushed off as “just another pregnancy symptom,” constipation can significantly impact daily comfort, sleep, and overall well-being.

Straining, bloating, and irregular bowel movements can make it harder to eat comfortably, rest well, or feel at ease in your body. When a symptom interferes with daily life, it’s worth addressing, and the good news is that pregnancy care providers expect this concern and can offer safe, evidence-based support.

What hormone imbalance causes constipation?

Progesterone rises early in pregnancy to help support the uterus and maintain pregnancy. One of progesterone’s key roles is relaxing smooth muscle, but that effect isn’t limited to the uterus. It also affects the digestive tract.

Dr. Carlsen explains, “Progesterone levels increase in the body during the time of pregnancy. Progesterone is a hormone that relaxes the muscles, such as the muscles in the intestines. Since the intestines will move more slowly, the waste will spend more time in the body, becoming harder and drier, thus causing constipation.” 

This is why constipation can show up even before your bump does, and why it often feels stubborn despite eating well. This isn’t a harmful imbalance or something going “wrong.” It’s a normal hormonal shift, but one that can still be uncomfortable and frustrating.

Why your growing uterus makes constipation worse

As pregnancy progresses, hormones aren’t the only factor affecting digestion. Physical pressure from the expanding uterus can also slow bowel movement, particularly in the second and third trimesters.

As space in the abdomen becomes more limited, the intestines have less room to function as efficiently as they did before. This is one reason constipation often worsens later in pregnancy, even if your diet, hydration, and routine haven’t changed much.

Add in fatigue, reduced movement, and iron supplements (which the Centers for Disease Control and Prevention (CDC) lists as a common contributor to constipation), and it becomes clear why digestion can feel increasingly sluggish over time.

Can an imbalance of gut bacteria cause constipation?

If meals suddenly leave you feeling uncomfortably full, gassy, or “off,” you’re not alone, and you’re not doing anything wrong.

In the first trimester, especially, your body is quietly adjusting in ways you can’t always see but can definitely feel. Pregnancy gently shifts the gut microbiome, the community of bacteria that helps your body digest food and absorb nutrients. These changes are a normal part of early pregnancy, but they can slow digestion and make your stomach feel more sensitive than usual. 

As Dr. Carlsen explains, “Another area affected by pregnancy is the gut microbiome. This is the bacteria present in the gut. It is a normal part of what helps facilitate the pregnancy, but can cause gas and bloating as well as slow digestion. It is very common for me to see patients who are experiencing fullness or irregularity even though they are eating a normal diet.”

What helps with constipation during pregnancy

The good news is that constipation during pregnancy often responds well to simple, consistent changes.

“Pregnancy-related constipation is not random; it’s a predictable consequence of hormonal, physical, and gastrointestinal changes. The most reliable and efficient ways to treat these conditions have been made simple after many years of experience,” says Dr. Carlsen

Guidance from the American Pregnancy Association (APA)  supports the following approaches as safe and effective first steps:

• Fiber from fruits, vegetables, and whole grains acts to soften the stool while ensuring that it moves.
• Water is necessary. Without sufficient water, fiber doesn’t digest properly.
• Activity, such as taking a daily walk, helps to stimulate bowel movement.
• Bulk-forming agents such as psyllium husk are both safe during pregnancy and very effective.
• Osmotic laxatives, like polyethylene glycol, may be tried when dietary changes are not adequate.

Dr. Carlsen advises, “patients against the excessive use of stimulant laxatives since they cause spasms.” If constipation isn’t improving, a healthcare provider can help guide next steps safely, especially before adding or changing medications.

Why early education matters

Untreated constipation can become more uncomfortable over time and increase the risk of complications, particularly as physical pressure increases later in pregnancy. Dr Carlsen adds, “Constipation can give rise to hemorrhoids, anal fissures, as well as pain in the pelvis. I would advise my patients to discuss their bowel habits in early pregnancy.”

Talking about bowel habits early can help prevent small issues from turning into more painful ones. It also gives you the chance to get support before discomfort starts interfering with daily life.

Conclusion

Understanding your body helps you feel more confident navigating pregnancy. If constipation is affecting your comfort, sleep, or mood, it deserves attention and care. You’re not overreacting. You’re responding to real, normal changes, and help is available.

Constipation during pregnancy can feel frustrating, uncomfortable, and sometimes isolating, but it’s a normal part of how your body adapts to pregnancy. You don’t have to tough it out, and you don’t have to feel awkward asking for help.

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Sources: 

1. Global pregnancy constipation prevalence meta-analysis. BMC Pregnancy and Childbirth. 2024. “Global prevalence of constipation during pregnancy: a systematic review and meta-analysis.” 
2. Physiology of pregnancy and undernutrition overview. National Academies Press (NCBI Bookshelf). 1992. “Physiology of Normal Pregnancy and the Effects of Undernutrition.” 
3. MedlinePlus patient guidance on common pregnancy symptoms including constipation. MedlinePlus (U.S. National Library of Medicine). (Accessed 2026). “Common symptoms during pregnancy: MedlinePlus Medical Encyclopedia.” 
4. Pregnancy constipation relief and management tips. American Pregnancy Association. (Accessed 2026). “Relieving Constipation During Pregnancy | Tips & Safe Remedies.“