29 August 2021
WHO recommendation on interventions for the relief of leg cramps during pregnancy
Magnesium, calcium or non-pharmacological treatment options can be used for the relief of leg cramps in pregnancy, based on a woman’s preferences and available options.
First published: November 2016
Updated: No update planned
Assessed as up-to-date: November 2016
Women’s bodies undergo substantial changes during pregnancy, which are brought about by both hormonal and mechanical effects. These changes lead to a variety of common symptoms – including nausea and vomiting, low back and pelvic pain, heartburn, varicose veins, constipation and leg cramps – that in some women cause severe discomfort and negatively affects their pregnancy experience. In general, symptoms associated with mechanical effects, e.g. pelvic pain, heartburn and varicose veins, often worsen as pregnancy progresses. Leg cramps often occur at night and can be very painful, affecting sleep and daily activities (1)
The ANC recommendations are intended to inform the development of relevant health-care policies and clinical protocols. These recommendations were developed in accordance with the methods described in the WHO handbook for guideline development (2). In summary, the process included: identification of priority questions and outcomes, retrieval of evidence, assessment and synthesis of the evidence, formulation of recommendations, and planning for the implementation, dissemination, impact evaluation and updating of the guideline.
The quality of the scientific evidence underpinning the recommendations was graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) (3) and Confidence in the Evidence from Reviews of Qualitative research (GRADE-CERQual) (4) approaches, for quantitative and qualitative evidence, respectively. Up-to-date systematic reviews were used to prepare evidence profiles for priority questions. The DECIDE (Developing and Evaluating Communication Strategies to support Informed Decisions and Practice based on Evidence) (5) framework, an evidence-to-decision tool that includes intervention effects, values, resources, equity, acceptability and feasibility criteria, was used to guide the formulation and approval of recommendations by the Guideline Development Group (GDG) – an international group of experts assembled for the purpose of developing this guideline – at three Technical Consultations between October 2015 and March 2016.
To ensure that each recommendation is correctly understood and applied in practice, the context of all context-specific recommendations is clearly stated within each recommendation, and the contributing experts provided additional remarks where needed.
In accordance with WHO guideline development standards, these recommendations will be reviewed and updated following the identification of new evidence, with major reviews and updates at least every five years.
Further information on procedures for developing this recommendation are available here.
For this recommendation, we aimed to answer the following question:
The evidence on the effects of various interventions for leg cramps in pregnancy is derived from a Cochrane review that included six small trials involving 390 pregnant women with leg cramps (1). Three studies from Norway (42 women), Sweden (69 women) and Thailand (86 women) contributed data on oral magnesium compared with placebo. One study from Sweden (43 women) compared oral calcium with no treatment; a study conducted in the Islamic Republic of Iran (42 women) compared oral vitamins B6 and B1 with no treatment; and another conducted in Sweden compared oral calcium with vitamin C (30 women). Symptom relief, measured in different ways, was the primary outcome in these studies, and other maternal and perinatal outcomes relevant to this guideline were not reported.
Oral magnesium versus placebo
In three small studies, women in the intervention group were given 300–360 mg magnesium per day in two or three divided doses. Studies measured persistence or occurrence of leg cramps in different ways, so results could not be pooled. Moderate-certainty evidence from the Thai study suggests that women receiving magnesium are more likely to experience a 50% reduction in the number of leg cramps (1 trial, 86 women; RR: 1.42, 95% CI: 1.09–1.86). The same direction of effect was found in the Swedish study, which reported the outcome “no leg cramps” after treatment, but the evidence was of low certainty (1 trial, 69 women; RR: 5.66, 95% CI: 1.35–23.68). Low-certainty evidence suggests that oral magnesium has little or no effect on the occurrence of potential side-effects, including nausea, diarrhoea, flatulence and bloating. Evidence from the third study was judged to be very uncertain.
Oral calcium versus no treatment
Calcium, 1 g twice daily for two weeks, was compared with no treatment in one small study. Low-certainty evidence suggests that women receiving calcium treatment are more likely to experience no leg cramps after treatment (43 women; RR: 8.59, 95% CI: 1.19–62.07). Oral calcium versus vitamin C Low-certainty evidence suggests that there may be little or no difference between calcium and vitamin C in the effect (if any) on complete symptom relief from leg cramps (RR: 1.33, 95% CI: 0.53–3.38).
Oral vitamin B1 and B6 versus no treatment
One study evaluated this comparison, with 21 women receiving vitamin B1 (100 mg) plus B6 (40 mg) once daily for two weeks and 21 women receiving no treatment; however, the low-certainty findings are contradictory and difficult to interpret.
The review found no evidence on nonpharmacological therapies, such as muscle stretching, massage, relaxation, heat therapy and dorsiflexion of the foot.
Magnesium and calcium supplements are relatively low-cost interventions, particularly when administered for limited periods of two to four weeks.
The potential etiology of leg cramps being related to a nutritional deficiency (magnesium) suggests that the prevalence of leg cramps might be higher in disadvantaged populations. In theory, therefore, nutritional interventions may have equity implications, but evidence is needed.
Qualitative evidence from a diverse range of settings suggests that women generally appreciate the pregnancy-related advice given by healthcare professionals during ANC, so may respond to supplement suggestions favourably (moderate confidence in the evidence) (6). Evidence from some LMICs suggests that women hold the belief that pregnancy is a healthy condition and may turn to traditional healers and/or herbal remedies to treat these kinds of associated symptoms (high confidence in the evidence).
Qualitative evidence suggests that a lack of resources may limit the offer of treatment for this condition (high confidence in the evidence) (7). In addition, where there are additional costs for pregnant women associated with treatment, women are less likely to use it.
Further information and considerations related to this recommendation can be found in the WHO guidelines, available at:
The GDG identified these priority questions related to this recommendation
WHO recommendations on antenatal care for a positive pregnancy experience
Citation: WHO Reproductive Health Library. WHO recommendation on interventions for the relief of leg cramps during pregnancy. (November 2016). The WHO Reproductive Health Library; Geneva: World Health Organization.
Citation: Whitworth M, Quenby S, Cockerill RO, Dowswell T. Specialised antenatal clinics for women with a pregnancy at high riskof preterm birth (excluding multiple pregnancy) to improve maternal and infant outcomes. Cochrane Database of Systematic Reviews 2011, Issue 9. Art. No.: CD006760. DOI: 10.1002/14651858.CD006760.pub2.Read Article
Citation: Catling CJ, Medley N, Foureur M, Ryan C, Leap N, Teate A, Homer CSE. Group versus conventional antenatal care for women. Cochrane Database of Systematic Reviews 2015, Issue 2. Art. No.: CD007622. DOI: 10.1002/14651858.CD007622.pub3.Read Article