Sodium supplements may decrease the number of cramp attacks experienced by women in pregnancy but the effect is slight. Calcium is of no benefit. The evidence of benefit for magnesium is stronger. Multivitamin and mineral supplements also seem to help but the relevance of this is unclear as the preparation used contained twelve separate constituents and it is not possible to discover which of these was effective, or indeed if there was synergy between constituents. There is a theoretical risk that sodium supplementation could raise blood pressure. It is unlikely that magnesium supplementation would be harmful at the suggested doses.
The evidence that calcium reduces cramp is weak and seems to depend on placebo effect. The evidence for sodium chloride is stronger but the results of the sodium chloride trial may no longer be relevant because of dietary changes which include an increased sodium intake in the general population. It is not possible to recommend multivitamins with mineral supplementation, as it is not clear which ingredient, if any, is helping. If a woman finds cramp troublesome in pregnancy, the best evidence is for magnesium lactate or citrate taken as 5mmol in the morning and 10mmol in the evening.
[Note: The five citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]
Many women experience leg cramps in pregnancy. They become more common as pregnancy progresses and are especially troublesome at night.
The objective of this review was to assess methods of preventing and treating leg cramps in pregnancy.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (October 2001). We updated this search on 4 July 2011 and added the results to the awaiting classification section.
Randomised trials of treatments for leg cramps in pregnancy.
Trial quality was assessed and data were extracted independently by two reviewers.
Five trials involving 352 women were included. The trials were of moderate quality. The only placebo-controlled trial of calcium treatment showed no evidence of benefit. Trials comparing sodium chloride with placebo (odds ratio 0.54, 95% confidence interval 0.23 to 1.29) and calcium with sodium chloride (odds ratio 1.23, 95% confidence intervals 0.47 to 3.27 ) showed no evidence of benefit. Placebo controlled trials of multivitamin with mineral supplements (odds ratio 0.23, 95% confidence intervals 0.05 to 1.01) and magnesium (odds ratio 0.18, 95% confidence intervals 0.05 to 0.60) provided some suggestion of benefit.