What causes leg cramps during pregnancy—and how to relieve the pain

After a long day of waddling around with your ever-growing baby belly, you finally settle in for some much-needed sleep. But just as you're about to drift off, you get a sharp pain in your calf that jolts you wide awake. There’s nothing quite like pregnancy leg cramps.  

What causes leg cramps?

Leg cramps are involuntary contractions of muscles at the back of the calf, and they often occur at night. Despite being a common pregnancy complaint, it’s not totally clear why they occur, says Amanda Selk, an OB/GYN at Women’s College Hospital in Toronto.

There are some theories, though. Leg cramps during pregnancy might be caused by fatigue, the uterus pressing on certain nerves, or decreased circulation in the legs from the pressure of the baby on blood vessels. They might also be caused by calcium or magnesium deficiency, or dehydration. But while being woken up by a sudden painful spasm is certainly unpleasant, leg cramps are generally nothing to worry about. (If they are severe and frequent, and are keeping you from sleeping, mention them to your health care provider at your next appointment.)

How can you relieve the pain?

In the midst of a spasm, try massaging your calf and flexing your foot, lifting your toes up and pushing your heel out, suggests Heather Martin, an Edmonton-based midwife. "Avoid pointing your toe—that exacerbates the cramping and can make it worse." You can also try standing on a hard floor and lifting your toes to stretch the calf muscle and stop the cramping, holding onto something if needed for balance. 

Can you prevent leg cramps?

You can certainly try! Slowly flexing and releasing your feet several times before bed each night can help keep leg cramps during pregnancy at bay. Wearing compression stockings, and avoiding sitting or standing for long periods of time may also reduce the occurrence of cramping. Calcium and magnesium supplements can help too, as can lots of water. Martin recommends pregnant women drink two to three litres a day, but not in large quantities, as gulping down too much water can cause heartburn, another common pregnancy ailment. 

Read more: Varicose veins during pregnancy: Symptoms and treatment What you need to know before booking a prenatal massage