Prevention of pregnancy-induced hypertension by calcium dietary supplement: a preliminary report.

OBJECTIVE

The purpose of this study is to clarify whether the taking of a calcium dietary supplement is able to prevent the development of pregnancy-induced hypertension (PIH) in Japanese people.

STUDY DESIGN

Forty-five nulliparous women (Ca-group) with various high-risk factors for PIH started to take a calcium supplement (1 g/day in the form of calcium salts) from the 12th gestational week (GW). Obstetrical outcome of Ca-group was compared to that of the nullipara (n = 453) who did not take a calcium supplement during pregnancy (Non-Ca Group) and that of the nullipara (n = 413) who did not develop PIH among Non-Ca group (normotensive group).

RESULTS

The incidence of PIH in the Ca-group was 2.2%, compared to 8.8% of Non-Ca group. The decrease in blood pressure after taking calcium during the first half of the pregnancy was much greater in Ca-group than in the normotensive group. The urinary excretion of sodium and calcium and serum free calcium at the 28th GW were much lower in a woman with PIH, despite of the taking of a calcium supplement, than in the normotensive calcium group. Also, the parathyroid hormone level at the 28th GW was higher in the calcium-taking woman with PIH than in the normotensive calcium group.

CONCLUSION

Our preliminary study suggests that among the possible effects of taking a calcium supplement are a decrease in blood pressure and the prevention of PIH in Japanese people, and that calcium metabolism might be related to the development of PIH. However, more study is needed before it will be possible to reach a final conclusion.