Study	Reason for exclusion
Aagaard 2005	This RCT looked at muscle strength, muscle mass and muscle magnesium content. It did not look at measures of muscle cramping
Bachem 1986	No control group. Article in German with English abstract. Methods translated
Bartl 1982	Did not appear to be randomized. Evaluated serum magnesium levels in pregnant cramp sufferers before and after magnesium supplementation. Did not evaluate changes in muscle cramping. Article in German with English abstract. Methods translated
Hammar 1987	No magnesium treatment arm
Häringer 1981	No control group. Article in German. Abstract and Methods translated
Riss 1983	Uncontrolled. Article in German with English abstract
Siegmund‐Schultze 2017	Not a trial. Article in German reviewing and commenting on Roguin Maor 2017
Weiss 2018	Not randomized
Weller 1998	This RCT looked at exercise performance and magnesium concentration in various tissues. It did not look at measures of muscle cramping
Zarean 2017	This RCT of pregnant women with hypomagnaesemia (only some of whom experienced muscle cramps) gave magnesium to the intervention group and not to the control group. However these 2 groups also appeared to take differing multimineral supplements (we attempted to confirm this with the trial authors but obtained no response). Our inclusion/exclusion criteria require treatment to be the same in each group, other than the provision of magnesium, and it is for this reason we chose to exclude the trial. This trial also looked at pregnancy outcomes more broadly, and did not focus on cramps. None of our specified outcomes were reported, only the number of unblinded participants self‐reporting "cramps" (yes/no) in each group

RCT: randomized controlled trial