Constipation in pregnancy: why it happens and what actually helps

Pregnancy · Updated July 2026 · All articles

Constipation affects more than half of all pregnant women at some point, making it one of the most commonly searched pregnancy symptoms. If you are spending longer in the bathroom, passing hard or infrequent stools, or feeling uncomfortable and bloated, you are far from alone. The good news is that there is a clear order of things to try, and if dietary changes are not enough, there are several laxatives that are safe to use during pregnancy. This article draws on NHS and NICE guidance to explain what is going on and what you can do about it.

Why constipation happens in pregnancy

There is not one single cause; rather, several things happen at once that together slow down your digestive system significantly.

Progesterone relaxes the gut

Progesterone is one of the most important hormones in pregnancy. It relaxes smooth muscle throughout the body to support the pregnancy, but that relaxing effect applies to the whole digestive tract, not just the uterus. The muscles that normally move food and waste through the bowel in rhythmic contractions (a process called peristalsis) slow down when progesterone levels are high. The result is that food and waste take longer to pass through, and the bowel has more time to absorb water from the stool, making it harder and drier.

Iron supplements

Many pregnant women are prescribed iron supplements, either routinely or to treat iron-deficiency anaemia. Iron is notoriously constipating: it can harden stools and, for some people, cause cramping and bloating as well. If your constipation started or got worse after beginning iron supplementation, this is very likely a contributing factor. See the section below on iron for what to do about it.

The growing uterus

As your pregnancy progresses, your uterus expands and takes up more space in the abdominal cavity. By the third trimester it presses directly on the large intestine and rectum, which can slow the passage of stools and make it physically harder to fully empty the bowel.

Reduced activity and dehydration

If morning sickness is making you reluctant to eat or drink, or if fatigue is keeping you more sedentary than usual, both things can worsen constipation. Physical movement stimulates bowel motility, and dehydration makes stools harder. Even mild, persistent nausea can affect how much fluid you are taking in without you realising.

When constipation tends to be worst

Many women notice constipation most in the first trimester, when progesterone levels surge rapidly. It often improves a little in the second trimester as the body adjusts, then returns with greater force in the third trimester when the growing uterus is at its most physically intrusive. That said, some women experience it throughout pregnancy, particularly if they are taking iron supplements the whole time.

What helps: diet and lifestyle first

Dietary and lifestyle changes are the right first step, and they work well for many women. Give them at least a week before reaching for a laxative.

Increase fibre, but do it gradually

Fibre adds bulk to the stool and keeps it soft enough to pass comfortably. There are two types and both are helpful.

Soluble fibre, found in oats, linseeds (flaxseeds), fruit and vegetables, dissolves in water to form a gel that softens the stool. Insoluble fibre, found in wholegrain bread, brown rice, bran cereals and the skins of fruit and vegetables, adds bulk and helps move things along more quickly. Aim to include both in your diet each day.

One important note: if you increase fibre too quickly, you may find that bloating and wind get worse before the constipation improves. Add a bit more fibre each day rather than overhauling your diet overnight, and drink more water alongside it.

Drink more fluids

Water is the single most important thing you can add. Aim for at least 8 glasses (around 2 litres) a day. A warm drink in the morning, before you have eaten anything, can help trigger the gastrocolic reflex, the natural urge to open your bowels that the gut produces in response to a full stomach or a warm fluid.

Prune juice is a well-known folk remedy that actually has evidence behind it. Prunes contain both fibre and sorbitol, a naturally occurring sugar alcohol that draws water into the bowel. A small glass (around 120 ml) in the morning is a reasonable thing to try.

Keep moving

Regular walking, even 20 to 30 minutes a day, helps stimulate the natural contractions of the bowel. You do not need to do anything strenuous. Gentle activity is enough, and it has the benefit of being good for your overall health and mood during pregnancy as well.

Do not ignore the urge

When you feel the urge to open your bowels, try to go. Repeatedly ignoring the urge trains the rectum to become less responsive over time and makes the stool harder and drier the longer it stays in the bowel. This can become a vicious cycle.

Try the footstool position

This one sounds small but makes a real difference. Placing your feet on a small footstool while on the toilet raises your knees above the level of your hips. This puts your body into a more natural squatting position, which straightens the anorectal angle and makes it significantly easier to empty the bowel without straining. You do not need a specialist product; a step stool, a stack of books, or even a box will do. Many people find this single change reduces straining dramatically.

What helps: laxatives that are safe in pregnancy

If dietary and lifestyle changes have not brought enough relief after about a week, laxatives are the next step. Several are considered safe to use during pregnancy, and your pharmacist or midwife can advise you on which to try first.

Bulk-forming laxatives (ispaghula husk, e.g. Fybogel)

These are the first-choice laxative option in pregnancy. They work by absorbing water in the bowel, increasing the bulk of the stool and stimulating the normal muscle contractions that move it along. The most widely used bulk-forming laxative is ispaghula husk, sold under the brand name Fybogel among others. It comes as a powder you dissolve in a glass of water and usually takes one to three days to work. It is important to drink plenty of water when taking it: without enough fluid, it can actually worsen constipation.

Osmotic laxatives (lactulose; Movicol / macrogol)

Osmotic laxatives soften the stool by drawing water into the bowel from the surrounding tissues. Lactulose is a syrup that has been used in pregnancy for many years and is considered safe. It tends to work gently but can take two to three days and may cause wind or bloating in some people. Movicol (which contains macrogol, also called polyethylene glycol) is another osmotic option that is also considered safe in pregnancy and is well tolerated by most people. Both are available over the counter from a pharmacy.

Stimulant laxatives (senna; bisacodyl)

Stimulant laxatives work by directly stimulating the nerve endings in the bowel wall, causing stronger muscle contractions and speeding up the passage of stool. Senna is the most commonly used stimulant laxative in pregnancy and has been widely used for many years. Bisacodyl is another option. These are generally used only short-term, and when bulk-forming or osmotic laxatives have not been effective on their own. They typically work within 6 to 12 hours. Discuss with your pharmacist or midwife before using a stimulant laxative, and always drink plenty of water alongside them.

What to avoid

High-dose castor oil should not be used in pregnancy. It is a powerful stimulant laxative that can cause strong uterine contractions and has historically been used to try to induce labour. It is not safe as a remedy for pregnancy constipation.

Iron supplements and constipation

If iron supplements are making your constipation significantly worse, the most important thing is not to stop taking them without talking to your midwife first. Iron deficiency anaemia in pregnancy carries real risks for you and your baby, and your midwife needs to know what is happening so they can find a solution that works.

There are several options they may suggest. A slow-release iron formulation is often better tolerated by the gut than standard ferrous sulfate tablets. Liquid iron supplements such as Spatone (a natural iron-rich water) and Floradix (a herbal iron tonic) are gentler on the digestive system for many people. Taking iron with orange juice rather than water can also help absorption and sometimes reduce side effects. Your midwife or GP is best placed to advise on what to switch to given your specific iron levels and circumstances.

Piles (haemorrhoids)

Constipation and straining are among the main drivers of haemorrhoids during pregnancy. Piles are swollen blood vessels inside or around the rectum and anus, and they are very common in pregnancy for the same hormonal and pressure-related reasons that cause constipation. Managing constipation well, staying hydrated, not straining on the toilet, and using the footstool position are all practical ways to reduce the strain that leads to piles. If you develop symptoms such as itching, soreness or bleeding around the back passage, let your midwife know. There are safe treatments available during pregnancy, and it is not something you have to put up with in silence.

When to see your midwife or GP

Most constipation in pregnancy responds well to the steps above. But there are situations where you should get in touch with your midwife or GP rather than managing things at home:

These symptoms are not necessarily serious, but they deserve proper assessment to rule out other causes and get you the right help quickly.

Frequently asked questions

Why am I constipated in pregnancy?

Constipation is very common in pregnancy because of a combination of factors. The hormone progesterone relaxes the smooth muscles of the digestive tract, slowing everything down. Iron supplements can harden stools. The growing uterus puts physical pressure on the bowel, especially in the third trimester. Reduced activity and dehydration from morning sickness also play a role.

Is it safe to take a laxative when pregnant?

Yes, several laxatives are considered safe to use in pregnancy. Bulk-forming laxatives such as ispaghula husk (Fybogel) are the first choice if dietary changes have not helped. Osmotic laxatives such as lactulose and Movicol (macrogol) are also considered safe. Stimulant laxatives like senna can be used short-term if other options have not worked. Always drink plenty of water with any laxative and check with your pharmacist or midwife before starting.

Does iron make constipation worse in pregnancy?

Yes, iron supplements are a common cause of harder, darker stools and constipation during pregnancy. If this is a problem for you, talk to your midwife before stopping your iron. They may be able to switch you to a slow-release formulation or suggest a gentler liquid iron source such as Spatone or Floradix, which are typically better tolerated.

What is the best thing to eat to help constipation in pregnancy?

Gradually increasing your fibre intake helps most. Good sources of soluble fibre include oats, linseeds, fruit and vegetables. Insoluble fibre from wholegrain bread and bran also helps move things along. Drink at least 8 glasses of water a day, try warm fluids in the morning, and include prune juice if you can tolerate it. Increase fibre slowly to avoid worsening bloating.

When should I see my midwife about constipation in pregnancy?

Contact your midwife or GP if constipation is severe, has not improved after two weeks of treatment, is accompanied by significant rectal bleeding, or comes with severe abdominal pain. These symptoms need assessment to rule out other causes.

Can constipation in pregnancy cause piles?

Yes. Straining to pass hard stools is one of the main causes of haemorrhoids (piles) during pregnancy. Managing constipation early, staying well hydrated, and not straining on the toilet are the best ways to reduce the risk. If you develop piles, let your midwife know as there are safe treatments available.

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