Calcium supplementation in pregnancy to prevent pregnancy induced hypertension (PIH).

Calcium supplementation during pregnancy has been studied since the 80's, epidemiologically and experimentally through laboratory animals and clinical trials. The findings showed the lowering of blood pressure and prevention of PIH in those receiving Calcium Supplementation. There were 22 clinical trials on Calcium supplementation since 1983; there were 5 trials added since Bucher et al made a meta-analysis on 14 of these trials in 1996. Three trials from Japan were added to the trials under study. A review of calcium homeostasis during normal pregnancy and PIH was added to allow a better understanding of physiologic and pathologic processes and how calcium supplementation works. The objective of this review is to show the rationale for supplementation of calcium during pregnancy to prevent PIH, hence the discussion on the latest investigations regarding etiology of PIH and the relation of Calcium to this causation. The USA large multicenter trial reported by Levine in 1997 contradicted the findings of all the previous random placebo controlled trials. Analysis of these trials showed that subjects were different; Levine trial used healthy nulliparas. The studies done in Japan, China and Philippines used a lower dose of Calcium but were effective. The conclusion of this review is Calcium supplementation helps those with high risk to develop PIH especially in countries where the calcium intake is low. Healthy nulliparas residing in countries with high Calcium intake will benefit less.