Gut Health During Pregnancy

Hey Baby! Gut Health During Pregnancy - Laura Tilt

From heartburn to constipation, changes in gut function are a normal (although often uncomfortable!) part of pregnancy. So what changes, and what can help ease discomforts?

Squeeze, shift and ouch!
As your baby grows in size they take up more real estate in your body, which means many of your internal organs shift or become somewhat squashed to accommodate their growing body - and that includes parts of the gut (watch how the body’s organs shift with each trimester in this clever animation).

By the time the end of pregnancy is reached, the stomach has swung upwards by about 45 degrees so that it sits atop the uterus. This means it has less room to expand, so eating larger (or even normal!) meals can become uncomfortable.

Increased pressure from a growing uterus and hormonal changes also cause the muscles at the bottom of the food pipe (oesophagus) to relax, so that acid can escape back upwards, triggering heartburn. This can be really uncomfortable, often flaring up in the third trimester.

What helps? If larger meals are a no no, opt for a little and often eating pattern or small meals and regular snacks. If you’re affected by heartburn, try to stay upright after eating (or prop yourself up with pillows), and sleep on your left side.

Some people find certain foods make heartburn worse - common trigger foods include fatty or greasy foods, caffeine, chocolate, tomatoes and citrus - worth reducing if you notice a link. You can also try over the counter antacids - medicines that neutralise stomach acid - but check with a pharmacist for a pregnancy suitable product.

Pooping problems
During pregnancy levels of the sex hormone progesterone soar in order to nurture the growing foetus and relax smooth muscles - including those in the large intestine.

This means food and waste products travel more slowly through your gut resulting in… yep, you guessed it, constipation. Studies show constipation is about two to three times more common in pregnant versus non pregnant women, making it the most common gut complaint after nausea.

As your baby gets bigger their position can also increase pressure on various parts of the intestines, making it more difficult to poop. Iron supplements can also be another cause of slow moving stools for mums to be affected by anaemia.

What helps? If you’re constipated, try to include plenty of foods rich in soluble fibre (think porridge oats, linseeds, root vegetables, prunes, kiwis, beans and lentils), drink plenty of fluid and try to get some daily movement like swimming or walking. If you’re still suffering after trying these steps, you can try an over the counter laxative that will help soften or bulk out your stools - but check with the pharmacist as to which is the safest kind - both lactulose and fybogel are suitable in pregnancy.

Another tip is no remember not to strain or hold your breath when you poop, as this can lead to haemorrhoids (swollen veins in your bottom) and fissures (small tears in the anal canal), and can affect your pelvic floor.

Instead, try popping your feet up on a stool or place a loo roll under each foot so that your knees are above your hips, as this helps the muscles that keep us continent to relax, making it easier to have a poo. If you can’t go, don’t strain - get up, have a hot drink, move around and try again in a little while.

Microbes, baby!
A less obvious change during pregnancy takes place with your gut microbiome - aka the collection of microbes and genetic material which live in your gut.

Studies show that the gut microbiome changes throughout pregnancy, as a normal and healthy adaptive response to growing a new life. The hormone progesterone has been shown to increase levels of bifidobacteria, which are required to break down the sugars in breast milk. Scientists think these microbes are increased during the later stages of pregnancy, so they can be transferred from mother to baby during vaginal delivery.

Research has also shown that certain bacteria are increased or decreased in order to train the baby’s immune system. Once baby is born, skin-to-skin contact and initiation of breastfeeding both play an important role in the early development of their own gut microbiome.

What helps? Research suggests that maternal diet during pregnancy can influence what microbes get transferred to the baby, with potential effects on their development in early life. A recent study found that a diet rich in fibre, omega-3 fats (from fish) and vegetable proteins was associated with positive effects on the newborn microbiome.

Try oats for breakfast, lentils in salads, and plenty of veggies in your evening meal. Including live yoghurt or milk kefir may also help to deliver beneficial microbes to your gut, and could also have other positive effects. One small study from Norway found that women consuming fermented milk products (like milk kefir) during the third trimester of their pregnancy had a lower risk of preeclampsia than non-consumers - but this could also be down to the calcium content of dairy, which is also thought to have a protective effect. Whilst no conclusions can be drawn from one study, calcium rich foods are a great thing to include during pregnancy as they’re important for the development of your baby’s bones. Try in a smoothie or pour over cereal.


1. Nagler R, Spiro HM. Heartburn in pregnancy. Am J Dig Dis. 1962;7(7):648-655. doi:10.1007/BF02232780

2. C.F. G, M. S, I. L, D. M, J. T. Gastrointestinal diseases during pregnancy: What does the gastroenterologist need to know? Ann Gastroenterol. 2018;31(4):385-394.

3. Turjeman S, Collado MC, Koren O. The gut microbiome in pregnancy and pregnancy complications. Curr Opin Endocr Metab Res. 2021;18:133-138. doi:10.1016/j.coemr.2021.03.004

4. García-Mantrana I, Selma-Royo M, González S, Parra-Llorca A, Martínez-Costa C, Collado MC. Distinct maternal microbiota clusters are associated with diet during pregnancy: impact on neonatal microbiota and infant growth during the first 18 months of life. Gut Microbes. 2020;11(4):962-978. doi:10.1080/19490976.2020.1730294

5. Nordqvist M, Jacobsson B, Brantsæter AL, Myhre R, Nilsson S, Sengpiel V. Timing of probiotic milk consumption during pregnancy and effects on the incidence of preeclampsia and preterm delivery: A prospective observational cohort study in Norway. BMJ Open. Published online 2018. doi:10.1136/bmjopen-2017-018021