What is the issue?
Leg cramps are experienced as sudden, intense involuntary contractions of the leg muscles. They are a common problem in pregnancy, especially in the third trimester. They are painful and can interfere with daily activities, disrupt sleep, and reduce quality of life. Various interventions have been used during pregnancy to treat leg cramps, including drug, electrolyte (magnesium, calcium, sodium) and vitamin therapies, and non-drug therapies such as muscle stretching.
Why is this important?
The goal of this review was to find out what is effective and safe for treating leg cramps during pregnancy.
What evidence did we find?
We searched for evidence in September 2019 and identified eight randomised controlled studies, with a total of 576 women who were 14 to 36 weeks pregnant, comparing either magnesium, calcium, calcium-vitamin D or vitamin B with placebo or no treatment, and comparing vitamin C with calcium. All treatments were given as tablets to be chewed or swallowed.
Magnesium supplements may reduce how often women experienced leg cramps when compared with placebo or no treatment, although findings were not consistent. Studies measured this in different ways, sometimes showing that magnesium helped reduce the number of leg cramps but sometimes showing that it made little or no difference. Likewise, evidence about whether magnesium reduced the intensity of pain was inconclusive with one study showing a reduction while others showed no difference. There was little or no difference in the experience of side effects, such as nausea and diarrhoea.
Calcium did not consistently reduce how often women experienced leg cramps after treatment compared to women who did not receive any treatment. The evidence was also found to be of very low quality and so we cannot be sure of the results.
More women who received vitamin B supplements fully recovered compared with those women receiving no treatment; however these results were from a small sample and the study had design limitations.
The frequency of leg cramps was no different between women treated with calcium and those treated with vitamin C.
The calcium‐vitamin D and the vitamin D supplements had no effect on the frequency, length, and pain intensity of leg cramps after treatment compared to women who received placebo.
What does this mean?
The level of evidence was found to be of low or very low quality. This was mainly due to the small sample size of studies and poor study design. Four studies were well-conducted and reported. The other four had design limitations: women were not allocated to different treatment groups in the best way in several studies, and in two studies women knew whether they were receiving treatment or not. Adverse effects such as any effect of the treatment on pregnancy complications, labour and the baby were not reported. Several of the studies focused mainly on serum calcium and magnesium levels. The frequency and intensity of cramps and the duration of pain were not reported in a consistent way and often information was lacking on how they were measured, either during treatment, at the end of treatment or after treatment had stopped.
It is not clear from the evidence reviewed whether any of the oral interventions (magnesium, calcium, calcium-vitamin D, vitamin B vitamin D or vitamin C) provide an effective and safe treatment for leg cramps in pregnancy. Supplements may have different effects depending on women's usual intake of these substances. No trials considered therapies such as muscle stretching, massage, relaxation or heat therapy.
It is unclear from the evidence reviewed whether any of the interventions provide an effective treatment for leg cramps. This is primarily due to outcomes being measured and reported in different, incomparable ways so that data could not be pooled. The certainty of evidence was found to be low or very-low due to design limitations and trials being too small to address the question satisfactorily.
Adverse outcomes were not reported, other than side effects for magnesium versus placebo/no treatment. It is therefore not possible to assess the safety of these interventions.
The inconsistency in the measurement and reporting of outcomes meant that meta-analyses could not be carried out. The development of a core outcome set for measuring the frequency, intensity and duration of leg cramps would address these inconsistencies and mean these outcomes could be investigated effectively in the future.
Leg cramps are a common problem in pregnancy. Various interventions have been used to treat them, including drug, electrolyte and vitamin therapies, and non-drug therapies. This Cochrane Review is an update of a review first published in 2015.
To assess the effectiveness and safety of different interventions for treating leg cramps in pregnancy.
We searched Cochrane Pregnancy and Childbirth’s Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (25 September 2019), and reference lists of retrieved studies.
Randomised controlled trials (RCTs) of any intervention for the treatment of leg cramps in pregnancy compared with placebo, no treatment or other treatments. Quinine was excluded for its known adverse effects. Cluster-RCTS were eligible for inclusion. Quasi-RCTs and cross-over studies were excluded.
Three review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. The certainty of the evidence was assessed using the GRADE approach.
We included eight small studies (576 women). Frequency of leg cramps was our primary outcome and secondary outcomes included intensity and duration of leg cramps, adverse outcomes for mother and baby and health-related quality of life. Overall, the studies were at low or unclear risk of bias. Outcomes were reported in different ways, precluding the use of meta-analysis and thus data were limited to single trials. Certainty of evidence was assessed as either low or very-low due to serious limitations in study design and imprecision.
Oral magnesium versus placebo/no treatment
The results for frequency of leg cramps were inconsistent. In one study, results indicated that women may be more likely to report never having any leg cramps after treatment (risk ratio (RR) 5.66, 95% confidence interval (CI) 1.35 to 23.68, 1 trial, 69 women, low-certainty evidence); whilst fewer women may report having twice-weekly leg cramps (RR 0.29, 95% CI 0.11 to 0.80, 1 trial, 69 women); and more women may report a 50% reduction in number of leg cramps after treatment (RR 1.42, 95% CI 1.09 to 1.86, 1 trial, 86 women, low-certainty evidence). However, other findings indicated that magnesium may make little to no difference in the frequency of leg cramps during differing periods of treatment.
For pain intensity, again results were inconsistent. Findings indicated that magnesium may make little or no difference: mean total pain score (MD 1.80, 95% CI -3.10 to 6.70, 1 trial, 38 women, low-certainty evidence). In another study the evidence was very uncertain about the effects of magnesium on pain intensity as measured in terms of a 50% reduction in pain. Findings from another study indicated that magnesium may reduce pain intensity according to a visual analogue scale (MD -17.50, 95% CI -34.68 to -0.32,1 trial, 69 women, low-certainty evidence). For all other outcomes examined there may be little or no difference: duration of leg cramps (low to very-low certainty); composite outcome - symptoms of leg cramps (very-low certainty); and for any side effects, including nausea and diarrhoea (low certainty).
Oral calcium versus placebo/no treatment
The evidence is unclear about the effect of calcium supplements on frequency of leg cramps because the certainty was found to be very low: no leg cramps after treatment (RR 8.59, 95% CI 1.19 to 62.07, 1 study, 43 women, very low-certainty evidence). In another small study, the findings indicated that the mean frequency of leg cramps may be slightly lower with oral calcium (MD -0.53, 95% CI -0.72 to -0.34; 1 study, 60 women; low certainty).
Oral vitamin B versus no treatment
One small trial, did not report on frequency of leg cramps individually, but showed that oral vitamin B supplements may reduce the frequency and intensity (composite outcome) of leg cramps (RR 0.29, 95% CI 0.11 to 0.73; 1 study, 42 women). There were no data on side effects.
Oral calcium versus oral vitamin C
The evidence is very uncertain about the effect of calcium on frequency of leg cramps after treatment compared with vitamin C (RR 1.33, 95% CI 0.53 to 3.38, 1 study, 60 women, very low-certainty evidence).
Oral vitamin D versus placebo
One trial (84 women) found vitamin D may make little or no difference to frequency of leg cramps compared with placebo at three weeks (MD 2.06, 95% CI 0.58 to 3.54); or six weeks after treatment (MD 1.53, 95% CI 0.12 to 2.94).
Oral calcium-vitamin D versus placebo
One trial (84 women) found oral calcium-vitamin D may make little or no difference to frequency of leg cramps compared with placebo after treatment at three weeks (MD -0.30, 95% CI -1.55 to 0.95); and six weeks (MD 0.03, 95% CI -1.3 to 1.36).
Oral calcium-vitamin D versus vitamin D
One trial (84 women) found oral calcium-vitamin D may make little or no difference to frequency of leg cramps compared with vitamin D after treatment at three weeks (MD -1.35, 95% CI -2.84 to 0.14); and six weeks after treatment (MD -1.10, 95% CI -2.69 to 0.49).