No one really understands why leg cramps are more common in pregnancy. They occur as painful involuntary contractions, typically of the muscles in the calf and foot and often strike at night during the second and third trimesters.

Theories on the causes of leg cramps include fatigue from carrying around the extra pregnancy weight, compression of the blood vessels in the legs by the expanding uterus, and dietary factors such as excess phosphorus or a shortage of calcium or magnesium.

Whilst the exact cause of cramps is not clear here are some tips that might help to prevent them:-

  1. Stretch your calf muscles.

Try giving your calf muscles a good stretch several times through the day and directly before you go to bed.

Stay active.

Regular exercise may help prevent leg cramps during pregnancy – take a walk every day (although always check with your doctor before starting an exercise regime).

Choose appropriate footwear.

Select shoes with comfort and support in mind.

Stay well hydrated.

Make sure you are drinking enough water and staying hydrated throughout the day.

Avoid getting too tired.

Take plenty of rest, and lie on your side to optimise the circulation to and from your legs.

Try a warm bath or shower before bed.

A warm bath can help relax the muscles.

Take a magnesium supplement.

There is some evidence that a magnesium supplement in pregnancy may help prevent leg cramps – always check with your doctor first.

You could consider including more magnesium-rich foods in your diet, such as whole grains, beans, dried fruits, nuts and seeds.

Although it has been suggested that leg cramps are a sign of calcium deficiency and that taking extra calcium may help, there is no good evidence that it makes any difference. In fact, one well designed study showed that taking calcium was no better than a placebo in preventing leg cramps in pregnant women. However, calcium is very important for lots of other reasons so make sure you have plenty in your diet.

And what do you do when the dreaded cramp strikes despite it all?

  • Immediately stretch your calf muscles – it may be painful initially but as the spasms ease, the pain will settle.

  • Then try to relax the muscle by gentle massage, applying a hot water bottle and taking a walk around for a few minutes.

  • Elevating the offending leg when you return to bed may also help to prevent the cramp from returning.