Leg cramps are a common and painful occurrence during pregnancy with about 30 – 50% of women experiencing them at some stage. They are caused by involuntary contractions of the muscles and usually strikes at night. The most common muscles affected are in the calf &/or foot and they tend to last for seconds or minutes and may also cause residual pain after the attack.
Whilst leg cramps are not a dangerous event in pregnancy they can limit exercise, affect daily activity, cause sleep disturbances and, as such, are linked to depression and a decrease in a woman’s quality of life. Such side effects may lead to other issues, such as increasing the length of labour and affecting the mode of birth.
There is limited research on the reason for leg cramps during pregnancy; however, muscle cramps are understood to occur from random discharges from motor nerves rather than the muscle itself.
There are several suggested methods to prevent and/or treat leg cramps during pregnancy; however, there is currently no consistent research and conclusion on the best method.
- Heat therapy
- Keep active
- Stay hydrated
- Wear comfortable shoes that support the heal
- Magnesium supplementation
How does magnesium help?
Magnesium is a mineral that our bodies need. A deficiency in magnesium leads to excitability and enhanced transmission of the nerve cells to muscles. The theory is that anything that can reduce the excitability of nerve impulses to a muscle should aid in preventing muscle cramps prophylactically. Therefore, it is believed that increasing magnesium in the body will relax the muscles.
Research in the effectiveness of magnesium supplementation is limited due to the small sample sizes of the studies and the differences in measurements in each study.
However, anecdotally, many women have discussed the benefits of magnesium supplementation decreasing the intensity and frequency of leg cramps. Clients from my clinic have also discussed the benefits of magnesium supplementation for leg cramps during pregnancy.
A recent study by Supakatisant and Phupong (2015) conducted a randomised controlled trial with a small sample size to determine the effectiveness of oral magnesium supplementation to reduce the intensity and frequency of leg cramps for pregnant women. The findings found a significant difference between women who took the supplementation compared to the women who took the placebo. Further trials are required to back up these findings.
- Higher doses of magnesium may cause diarrhoea
- Overuse of magnesium may cause weak muscles, thirst, dry mouth, flushing, low blood pressure or confusion
How to take magnesium
- Available in oral tablets or liquid form
- Many multi-vitamins contain small doses magnesium; however, for leg cramps, an additional supplement may be required
- Discuss with your health care provider as many magnesium supplements are blended, or specifically designed for cramps
- Magnesium doses up to 400mg are classified under Category A for medicines in pregnancy (meaning a large number of pregnant women have taken magnesium without any observation of increase in harmful effects to a fetus)
- The following interact with magnesium and should be taken at different times: calcium, iron, antibiotics and blood pressure medication
Magnesium rich foods
- Dark green leafy vegetables
- Legumes (beans, lentils, etc.)
- Unrefined grains
Harms, R. W. (2013). What causes leg cramps during pregnancy, and can they be prevented? Retrieved from http://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/leg-cramps-during-pregnancy/faq-20057766
Supakatisant, C., & Phupong, V. (2015). Oral magnesium for relief in pregnancy‐induced leg cramps: A randomised controlled trial. Maternal & Child Nutrition, 11(2), 139-145. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22909270
Garrison, S. R., Allan, G. M., Sekhon, R. K., Musini, V. M., & Khan, K. M. (2012). Magnesium for skeletal muscle cramps. The Cochrane Database of Systematic Reviews, 9, CD009402. Retrieved from https://www.researchgate.net/publication/230842970_Magnesium_for_skeletal_muscle_cramps_Protocol
Sebo, P., Cerutti, B., & Haller, D. M. (2014). Effect of magnesium therapy on nocturnal leg cramps: A systematic review of randomized controlled trials with meta-analysis using simulations. Family Practice, 31(1), 7-19. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/24280947