Calcium and magnesium status in pregnant women. A comparison between treatment with calcium and vitamin C in pregnant women with leg cramps. Effects of a multivitamin mineral supplement on zinc and copper status during pregnancy. The effect of oral magnesium substitution on pregnancy-induced leg cramps. Calcium treatment of leg cramps in pregnancy. Effect on clinical symptoms and total serum and ionized serum calcium concentrations.
60 pregnant women underwent a double blind trial with calcium or ascorbic acid (1 g twice daily) as treatment for leg cramps. There was no significant difference between the two treatment groups with respect to clinical improvement. In 14 out of 60 patients the symptoms were totally abolished and in another 27 patients the symptoms were significantly decreased by the treatment (irrespective of drug used). In 17 patients the symptoms were unaffected while only two patients experienced an increase in frequency of their leg cramps during therapy. Serum total and ionized calcium concentrations, serum total magnesium and albumin concentrations were determined and were not significantly changed throughout therapy in any of the groups. No biochemical differences were found between the different treatment regimens or between those patients relieved or not relieved of their symptoms. Serum magnesium concentrations were at or just below the lower normal limit (for non pregnant women) in treated women and pregnant controls. The effect of a multivitamin-mineral supplement was investigated during pregnancy according to a double-blind protocol by determining zinc and copper in maternal plasma, mononuclear and polynuclear zinc and copper at the third, sixth, eighth, and ninth months of gestation. The subjects were supplemented from the first trimester until delivery. A significant decrease was observed in plasma zinc that varied from 11.5 mumol/L to 10.8 mumol/L in the supplemented group (n = 29) and from 11 mumol/L to 10 mumol/L in the placebo group (n = 33) at 3 and 9 mo of gestation, respectively. In contrast, plasma copper levels increased in a way depending upon the stage of gestation in both groups: from 24.7 to 28.2 mumol/L in the treated group and from 24.9 to 30.9 mumol/L in the placebo group at 3 and 9 mo of gestation, respectively, but the difference was only significant in the placebo group. No difference between groups was observed in mononuclear and polynuclear zinc or copper levels. These trace elements were also determined in cord blood at delivery. There were no statistically significant differences in zinc and copper concentration found in placebo group and supplemented group. Finally, the beneficial effect of supplementation on muscular cramps and appearance of vergetures was noted. Our purpose was to determine whether women with pregnancy-related leg cramps would benefit from oral magnesium supplementation.
                Seventy-three women with pregnancy-related leg cramps were interviewed about their symptoms in a prospective, double-blind, randomized trial. Initial serum magnesium levels and diurnal magnesium excretion was determined in 50% of the patients. Oral magnesium or placebo was given for 3 weeks, after which new interviews and laboratory analyses were performed.
                Serum magnesium levels in these patients were at or below the lower reference limit, as is also often the case in healthy pregnant patients. Oral magnesium substitution decreased leg cramp distress (p < 0.05 compared with the placebo group, p < 0.001 compared with initial complaints), but did not significantly increase serum magnesium levels, excess magnesium being excreted as measured by an increase in urinary magnesium levels (p < 0.002).
                Oral magnesium supplementation seems to be a valuable therapeutic tool in the treatment of pregnancy-related leg cramps. Up to 30 per cent of pregnant women suffer from leg cramps. The cause of these cramps is not known, but changes in calcium concentration have been suggested. Therefore 42 pregnant women with leg cramps were studied. No differences in total serum or ionized serum calcium concentrations were found as compared with a control group of pregnant women without leg cramps. Twenty-one patients were treated with 1 g calcium orally twice daily for 2 weeks and in this group good clinical improvement was achieved (p less than 0.001). The treatment increased the total serum calcium concentration from 2.25 mmol/l to 2.30 mmol/l but did not alter the ionized serum calcium concentration. Twenty-one untreated patients had the same frequency of cramps and showed no change in serum calcium concentrations throughout the investigation.
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.]