Calcium supplementation reducing the risk of hypertensive disorders of pregnancy and related problems: A meta-analysis of multicentre randomized controlled trials.

Hypertensive disorders of pregnancy are closely related to maternal mortality and morbidity. Calcium supplementation during pregnancy seems to reduce the risk of hypertensive disorders. No systematic review on multicentre RCTs of calcium supplementation during pregnancy has been published. The purpose of this study was to report a quantitative systematic review of the effectiveness of calcium supplementation during pregnancy on reducing the risk of hypertensive disorders of pregnancy and related problems. Publications over the years of 1991-2012 were searched through PubMed, Science Direct, EMBASE, CINAHL and Web of Science. The literatures were selected of the multicentre RCTs on calcium supplementation during pregnancy in prevention of hypertensive disorders and related problems. Reference lists from the studies were also examined for additional references. Studies were critically appraised by three independent reviewers, and the Cochrane Handbook was used to assess the quality of those included trials. Four studies were included in this systematic review. All included studies were high quality, with low risk of bias. There was an observed risk reduction in hypertension in calcium group. However, there was no reduction in the risk of severe gestational hypertension, pre-eclampsia, severe pre-eclampsia, preterm birth and low birthweight. Calcium supplementation appears to reduce the risk of hypertension in pregnancy.