Interventions for leg cramps in pregnancy.
Level 1 - systematic review of randomized trials
Systematic review of randomized controlled trials
PubMed 33275278 · doi:10.1002/14651858.CD010655.pub3
What was done
Authors searched the Cochrane Pregnancy and Childbirth Trials Register, ClinicalTrials.gov, WHO ICTRP (through September 2019), and reference lists for randomized controlled trials evaluating any non-quinine intervention for leg cramps in pregnancy compared to placebo, no treatment, or alternative therapies. Three review authors independently selected studies, extracted data, assessed risk of bias, and evaluated evidence certainty using GRADE. Eight trials comprising 576 women were included.
What was found
Heterogeneous outcome measures prevented pooling via meta-analysis. For oral magnesium versus placebo/no treatment, results for cramp frequency were conflicting across single trials: one trial (n=69) reported higher likelihood of no cramps post-treatment (RR 5.66, 95% CI 1.35 to 23.68) and fewer twice-weekly cramps (RR 0.29, 95% CI 0.11 to 0.80), and another (n=86) reported 50% cramp reduction (RR 1.42, 95% CI 1.09 to 1.86), while other measures showed no clear difference. Magnesium pain intensity effects were also inconsistent (MD 1.80, 95% CI -3.10 to 6.70 in 38 women; VAS MD -17.50, 95% CI -34.68 to -0.32 in 69 women). Calcium versus placebo showed very low certainty results for no cramps (RR 8.59, 95% CI 1.19 to 62.07, 1 study, n=43) and frequency reduction (MD -0.53, 95% CI -0.72 to -0.34, 1 study, n=60). Vitamin B reduced a composite frequency/intensity outcome (RR 0.29, 95% CI 0.11 to 0.73, 1 study, n=42). Vitamin D, calcium-vitamin D, and calcium versus vitamin C showed no clear benefits.
Why it matters
Leg cramps are common during pregnancy, but this review shows that commonly recommended nutritional supplements like magnesium, calcium, and vitamins lack reliable evidence of benefit.
Limits
All included studies were small (total n=576 across 8 trials), with low or unclear risk of bias and low to very low GRADE certainty due to imprecision and design limitations. Outcomes were measured inconsistently across studies, preventing meta-analysis. Data on maternal and fetal safety were largely absent, except for limited reporting of mild gastrointestinal side effects for magnesium.
Cited by
- supports Evidence supporting magnesium supplementation for reducing muscle cramps is generally weak, though some studies suggest benefits in pregnant women.