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Constipation in Pregnancy: Complete Guide

Constipation is one of the most common — and most rarely talked about — pregnancy symptoms, and it can start as early as the first trimester. It's caused by a mix of hormonal changes, iron supplements, and later on, physical pressure from your growing uterus. The good news is that it usually responds well to simple, pregnancy-safe changes to diet, fluids, and movement.

Why pregnancy causes constipation

  • Progesterone relaxes smooth muscle throughout your body, including the muscles in your bowel wall, which slows down how quickly food moves through your digestive system.
  • Iron supplements, often started early in pregnancy or after a routine blood test shows low iron, are a well-known cause of harder, less frequent stools.
  • Reduced activity levels, if nausea or tiredness mean you're moving less than usual, can make sluggish digestion worse.
  • Pressure from the uterus on your bowel becomes more noticeable as pregnancy progresses, particularly in the second and third trimesters.
  • Dehydration, especially if you're also dealing with morning sickness, reduces the water content of stools and makes them harder to pass.

Safe ways to ease constipation

Diet and lifestyle changes are the first line of treatment in pregnancy, and for many women they're enough on their own.

  • Increase fibre gradually through fruit, vegetables, wholegrain bread and cereals, oats, and pulses — a sudden jump can cause bloating, so build up over a few days.
  • Aim to drink plenty of water throughout the day; herbal teas and diluted squash count too.
  • Stay as active as you comfortably can — a daily walk, swimming, or pregnancy yoga all help keep digestion moving, in line with the general NHS guidance of building up to around 150 minutes of moderate activity a week.
  • Try not to ignore the urge to go, and give yourself time and privacy rather than rushing.
  • Prunes, prune juice, and linseeds are traditional, gentle options some women find helpful alongside a high-fibre diet.

When a laxative might help

If diet and lifestyle changes aren't enough, speak to your midwife, GP, or pharmacist before starting anything.

  • Bulk-forming laxatives such as ispaghula husk (Fybogel) are generally considered suitable in pregnancy and work by adding fibre and fluid to your stool.
  • Osmotic laxatives like lactulose can also be used under guidance, as they draw water into the bowel to soften stools.
  • Stimulant laxatives (such as senna) are usually avoided unless specifically recommended by a healthcare professional, as they work differently and are not typically first choice in pregnancy.
  • If you're taking iron supplements and constipation is a significant problem, mention this to your midwife — sometimes a different dose or formulation can help.

When to get medical advice

Most constipation in pregnancy is uncomfortable rather than dangerous, but contact your midwife or GP if you notice:

  • Severe abdominal pain, or pain that doesn't ease after opening your bowels.
  • Blood in your stool, or on the toilet paper, that doesn't seem to be from a minor haemorrhoid.
  • No improvement at all despite several days of diet, fluid, and activity changes.
  • Constipation alongside vomiting, fever, or feeling generally unwell.

Frequently Asked Questions

Is constipation normal in pregnancy?

Yes, it's a very common symptom, particularly linked to rising progesterone levels and, for some women, iron supplements. It can happen at any stage of pregnancy but often becomes more noticeable as the uterus grows. It's uncomfortable rather than a sign that something is wrong, and it usually responds well to diet and lifestyle changes.

What laxatives are safe to take in pregnancy?

Bulk-forming laxatives like ispaghula husk (Fybogel) and osmotic laxatives like lactulose are generally considered appropriate options, but you should always check with your midwife, GP, or pharmacist before starting one. Stimulant laxatives such as senna are usually only used if specifically advised by a healthcare professional. Never start a new medicine or supplement in pregnancy without checking it's suitable first.

Can iron tablets make constipation worse?

Yes, iron supplements are a well-recognised cause of constipation and harder stools in pregnancy. If this is a problem for you, don't stop taking iron without medical advice, as it's often prescribed for a good reason — instead, mention it to your midwife, who may suggest a different type or dose, alongside the usual diet and fluid measures.

This article is for informational purposes only and does not constitute medical advice — always speak to your midwife or GP about symptoms in your own pregnancy.

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