Lin Chang, MD, on IBS and Pregnancy

Dr Chang recaps her presentation at ACG 2025 on how pregnancy can affect irritable bowel syndrome and how to best treat pregnant patients with IBS.

Lin Chang, MD, is Professor of Medicine and Vice Chief of the Vatche & Tamar Manoukian Division of Digestive Diseases at UCLA in Los Angeles, California.

CLINICAL PRACTICE SUMMARY:

• Hormonal impact on GI motility and reflux: Elevated estrogen and progesterone during pregnancy relax GI smooth muscle, slowing intestinal transit and relaxing the lower esophageal sphincter. This leads to early-onset constipation and GERD symptoms—often beginning by the end of the first trimester, independent of uterine size.
• IBS and pregnancy outcomes: Limited data show women with irritable bowel syndrome (IBS) may have a ~20% higher miscarriage risk versus non-IBS controls, but most experience stable or improved symptoms during pregnancy. Further research is needed to clarify IBS course and outcomes in pregnancy.
• Constipation management in pregnancy: First-line therapies include fiber (psyllium), magnesium-based osmotic laxatives, and polyethylene glycol (Miralax). Lactulose may be used but can cause bloating. Prescription options such as lubiprostone or linaclotide are generally reserved when benefits outweigh risks; prucalopride is not recommended. For IBS with diarrhea, short-term loperamide is acceptable. SSRIs (sertraline, citalopram) and SNRIs (duloxetine) may be used for comorbid mood or pain symptoms under OBGYN guidance, prioritizing maternal health

TRANSCRIPT:

I am Lin Chang. I'm a gastroenterologist professor of medicine and Vice Chief of the VCE and Tamara Manukian Division of Digestive Diseases at UCLA in Los Angeles. And I'm at the ACG meeting where I presented a lecture on the impact of pregnancy and how it affects IBS and chronic constipation. And what I found out was a lot of interesting information.

I study a lot about sex differences in IBS and constipation. And we know that during pregnancy, estrogen and progesterone are very high. And what it can do to the GI tract function is that estrogen and progesterone can relax the smooth muscle of the gastrointestinal tract. So that can lead to symptoms such as constipation because it slows transit,time of contents through the GI tract. Also, it can relax a muscle called the lower esophageal sphincter, which is a muscle that separates the esophagus and the stomach and when that muscle relaxes due to estrogen and progesterone, women can have more acid reflux during pregnancy.

And this can occur fairly early in pregnancy at the end of the first trimester and second trimester. So it's not really because the uterus is larger, it's even earlier in pregnancy, and it's due to the effect of estrogen, progesterone on smooth muscle in the gut.

And as I said, constipation is another common symptom that women can have. They can already have constipation, it could get worse or they never had constipation, but they have it during pregnancy. Also, there's nausea and vomiting disorders that can occur. Some women have something called hyperemesis gravidarum, but there's other causes of nausea, vomiting in pregnancy, which is typically earlier in pregnancy.

Patients can have GERD, as I said, gastroesophageal reflux disease, and constipation. Now, IBS, there's not that much is known about irritable bowel syndrome and what happens when women get pregnant. A lot of women will have IBS preceding their pregnancy.

There is evidence in a large database study that women with IBS, where they have chronic abdominal pain with diarrhea, constipation, or both, they can have an 20% increase in miscarriage compared to women who don't have IBS. But we don't have that much data and my experience has been that many women with IBS do very well during pregnancy. So that is another area of research that is an unmet need that would be really great if we can get more information on that.

And then for constipation, we have to think about the treatments. So some women are taking iron or calcium during pregnancy, and both of those medications can be constipating. So there could be multiple reasons why a woman has more constipation during pregnancy. If we think about the treatments for constipation, because that's such a common question, I'm thinking about getting pregnant or I am pregnant or I'm breastfeeding or can I take, and in general, of course, fiber, psyllium, that can be very safe in pregnancy. Magnesium based laxative—and many people may not know this— but magnesium acts as an osmotic laxative, meaning that it draws water into the gut and it helps constipation symptoms and makes stool more formed, less hard, and makes the stool flow through the GI tract faster. And there's different magnesium based laxatives, which are safe to use.

There's also the other over-the-counter remedy, polyethylene glycol, and you may know the name by Miralax, that also can be used during pregnancy. There's another prescription medication called lactulose. Often it's not used that much in constipation just in general these days. It's used for other conditions because it can cost some bloating and gas and many patients with constipation already have those symptoms, so it's not used very often, but it can be used during pregnancy.

Now there are prescription medications like lubiprostone, linaclotide for chronic constipation ,that really stay in the gut, but there's really not that much data. There used to be data with lubiprostone that thought you don't use it in pregnancy. But a few years ago there was a very nice review that really looked at the literature and it doesn't appear that it has the effects, the negative effects on pregnancy as previously thought based on more data. But in general, these medications are used only if the benefit outweighs the risk.

So if there's other strategies to use—dietary, over the counter remedies that are safe to use in pregnancy, that's really what's recommended. Prucalopride is a different type of constipation agent where it increases contractions in the gut, helps chronic constipation, that currently is not recommended to use during pregnancy.

Now we have to think about IBS where some patients have constipation, but they could have diarrhea or they could have pain. Where in chronic constipation, pain may not be a predominant symptom.  So in general, loperamide or Imodium is safe to use, just short doses for diarrhea. Also, we talk a lot about medications that we call neuromodulators and they work by working on the nerves to help reduce abdominal symptoms. Many of these can also be used for their effects on mood like anxiety or depression. If you look at the guidelines by OBGYN Association, they think about more of these neuromodulators or antidepressants, antianxiety agents for depression, anxiety, and the recommendation by their society is to treat these mood disorders if it's a benefit to the mother. And you can use behavioral therapy, psychological therapy where there's no medication, and you can also use antidepressants or antianxiety agents like SSRIs, and it's safer to use sertraline or citalopram more than paroxetine, which is not recommended to use during pregnancy. If a woman can't take an SSRI because they don't tolerate it, they can use an SNRI, which is a serotonin noradrenergic reuptake inhibitor like duloxetine. That can be a second line agent.

In general, there's less support for using tricyclic antidepressants, which are like amitriptyline, desipramine, by the OB GYN association. However, if you look at the gastrointestinal literature, that comes from the viewpoint of using those neuromodulators, not so much for mood disorders, but for abdominal symptoms like pain and bloating and discomfort, and from that standpoint, using lower doses of a tricyclic is thought to be safe to do and also to use SNRIs or SSRIs. I think the take home point here is to recommend treatment for the mother to have a healthy mother. That's the benefit outweighs the risk. And if you can use any types of remedies that are safe for the mother, then you should do that. If though medications are needed because it's healthier for the mother to carry the baby through to term, then it would be recommended to do that just with some monitoring.