What's the deal with constipation during pregnancy?
Constipation during pregnancy is SO common. In fact, it's the second-most common gastrointestinal disorder during pregnancy behind nausea and vomiting. 11-40% of pregnant people are constipated according to the official diagnostic criteria I outlined in previous articles. Most of the time, studies report a constipation rate of 30-40% as being most common. But if you ask pregnant people to self-report symptoms, as many as 61% will say they feel constipated! And yet, despite its commonness, it's woefully under-studied and under-treated.
Why do people become constipated during pregnancy?
There are so many contributing factors to the slowing down of your bowels during pregnancy. I'll provide a laundry list here:
high progesterone (especially in the first trimester) slows down gut motility, e.g. the ability of your colon to move your waste through your gut
relaxin slows small bowel contractions (peaks at end of first trimester but is present throughout pregnancy)
pressure of the pregnant uterus compresses/obstructs the colon in the third trimester
decreased physical activity because you feel crappy!
hormone changes cause increased water absorption in your colon, leading to hard, lumpy stools
medications, such as iron and some anti-nausea/vomiting meds have side effects of constipation
fluid loss from vomiting
maternal gut microbiome changes
reduced fiber and water intake (again, because you feel like crap, and/or have food aversions)
rectal pain from hemorrhoids or anal fissures (more on this later)
I will also add, although this isn't in the literature, that a growing belly means you can't use your abdominal muscles as effectively to push for your bowel movements (BMs) Plus, we know diastasis rectus abdominis (DRA) is a contributing factor to constipation, and 100% of pregnant people will have a DRA by week 35 of pregnancy.
What are risk factors for constipation in pregnancy?
You are more likely to struggle with constipation while pregnant if any of the following applies to you:
decreased physical activity
being placed on bedrest
low fiber intake
decreased fluid intake
using iron supplements
Will my doctor order any tests to determine if I am constipated?
Most likely not. As with most other medical issues during pregnancy, we avoid putting a pregnant body through general medical testing as much as possible to avoid harm to the fetus. The only exception to this is bloodwork, as your doctor may want to check you for a low thyroid or diabetes. So, unless you have fecal impaction or have a severe obstruction of your colon, most of the time your doctor will just take your word for it that you are constipated.
What can I do about constipation in pregnancy?
First, the basics, as always! Make sure you are moving your body, getting plenty of fluid, and increase your fiber intake to higher than your typical levels. Of course, this all comes with the caveat that you are likely feeling crappy, so don’t push your body beyond its limits. Here are some basic recommendations:
drink at least 8 glasses of water/day
eat 25-40 grams of fiber/day
eat smaller, more-frequent meals in the second and third trimesters particularly
I will say though, at least one study does show that increasing fiber and fluid alone is not enough to reduce the symptoms of constipation during pregnancy. It is likely that the hormonal changes are so strong in the first and second trimesters in particular, that making changes to your diet isn’t enough to overcome the effects of these hormones. However, this same study did show that low fiber intake was linked to worse pregnancy outcomes. Specifically it was linked to C-section deliveries, prematurity, and/or fetal growth restriction. We do know that high fiber diets can reduce the risk of things such as high blood pressure and diabetes, which in a pregnant person can of course cause negative outcomes for the mom and fetus. So it is possible that eating a high fiber diet in pregnancy can have benefits beyond your bowels.
And, make sure you know how to sit on the toilet and “push” correctly for bowel movements. If not, please refresh yourself with my first constipation article! Small changes like a stool underneath your feet can make a big impact!
Plus, for most people, constipation is worst in the first and second trimesters. So one thing you can actually look forward to about your third trimester is possibly being less constipated!
If I’m good on fiber and fluid, what’s next?
As I said above, many times just upping fiber and water isn’t enough. The good news is that many of the same over-the-counter laxatives you can take when not pregnant are also safe for pregnancy. However, I will say that in general studies on supplements and medications in pregnancy are very sparse. The data that is there generally is of low quality with a high risk of bias. So, every person needs to talk to their OB/midwife, and weigh the benefits vs the risks of taking supplements or laxatives in their own bodies.
Here’s a run-down of some options:
Fiber supplements, aka bulk-forming laxatives: psyllium (Metamucil, or you can take this in pill form as psyllium husk), methylcellulose (Citracel), guar, calcium polycarbophil, pectin, and flax seed (ground or whole) are all generally safe and often effective in pregnancy. Fiber supplements do seem to be effective as compared to no intervention at increasing stool softness and frequency in pregnancy. However, stimulant laxatives are more effective than fiber supplements, but come with the risk of abdominal discomfort and diarrhea. And as always, if you are adding in fiber, do so slowly as too much in a short period of time can cause increased bloating and gas.
Osmotic laxatives: Polyethylene glycol (aka PEG or Miralax), lactulose, sorbitol, and glycerin are all options that are generally safe for pregnancy, as their mechanism of action is drawing more water into the colon. Osmotic laxatives are not well-absorbed by the intestine, so very little is absorbed into your bloodstream and thus not passed to the fetus. However, saline hyperosmotic laxatives are best to be avoided in pregnancy, as they can result in fluid retention.
Lubricants: the use of mineral oil and castor oil is best avoided in pregnancy as it can lead to reduced absorption of certain vitamins, and cause premature uterine contractions.
Stimulant laxatives: These can be a reasonable option if fiber and osmotic laxatives don’t do the trick. Senna and bisacodyl are the most common ones, and are minimally absorbed into your bloodstream. However, senna in particular has been linked to reports of fetal death at higher doses (4%) and has conflicting safety data. It also may cause an electrolyte imbalance if it ends up causing you diarrhea. And as I alluded to above, these work by causing intestinal cramping and so sometimes are not well-tolerated.
Stool softeners: Ducosate sodium, also known as Colace, is typically the first thing that is recommended by doctors for pregnant people. However, it’s well-known that ducosate sodium is found to be no better than placebo in very large, high-quality studies of the general population. So unfortunately, there really is no evidence to show that it works for anyone, regardless of pregnancy status. But since it’s generally well-tolerated without side effects, it is commonly recommended even though the evidence doesn’t support its use. I will say though, if you think it’s working for you, don’t stop it just because of this information! If you stop it and your constipation gets worse, definitely continue. But if you stop it and you don’t notice a change, you are best off trying something different.
What about postpartum constipation, and that typically-awful first bowel movement after delivery?
Ugh, that first BM after having a baby can be the. worst. This is regardless of delivery mode, because if you have a vaginal delivery (especially with tearing), the thought of pushing anything else out down there is terrifying! This is especially true if you are worried about tearing stitches. And for my C-section moms, your abdominal pain is so great that having to use those abdominals to push or create any force is pretty awful. Plus, pain makes your muscles tighten up, so even just trying to relax your pelvic floor to get your stool out is a tall ask.
The tough part about answering this question is that the evidence is VERY poor. A Cochrane review from 2020 only found 5 studies to review, and 4 of them were completed over 40 years ago. Which means also some of them studied supplements or drugs that we no longer think are safe for people who breast or chest feed. And the trials that were left are so small and the evidence so poor that really no great conclusions can be drawn from them.
I will say that especially for a vaginal delivery, if you try what is called “splinting” of your perineum, this may help. You take your fingers, or a wad of tissue paper, and push “upwards” slightly towards your head on your perineum (aka the area between your vagina and rectum). This can provide support to sore/lengthen/torn tissues, and give you some counterpressure to the “push” for the BM.
Additionally, the basics are KEY here. Lots of diaphragmatic breathing, relaxation, feet on a stool, and water/fiber to make your stool as soft as possible can be incredibly helpful.
Nagaich, N., Sharma, R., & Nair, N. Gastrointestinal Diseases in Pregnancy; Diagnosis and Management. Gastro Med Res. 2(4). GMR.000544. 2019. DOI: 10.31031/GMR.2019.02.000544
Rao, S. S. C., Qureshi, W. A., Yan, Y., & Johnson, D. A. (2022). Constipation, Hemorrhoids, and Anorectal Disorders in Pregnancy. The American journal of gastroenterology, 117(10S), 16–25. https://doi.org/10.14309/ajg.0000000000001962
Turawa, E. B., Musekiwa, A., & Rohwer, A. C. (2020). Interventions for preventing postpartum constipation. The Cochrane database of systematic reviews, 8(8), CD011625. https://doi.org/10.1002/14651858.CD011625.pub3