WHO calcium supplementation trial for the prevention of pre-eclampsia among low calcium intake women

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Hypertensive disorders of pregnancy (HDP) affect approximately 10% of all pregnancies. The aetiology and pathophysiology of HDP are still largely unknown and an ideal prevention and treatment strategy does not exist. Although there has been progress in perinatal survival, largely due to developments in care of small babies, HDP continue to be major contributors to maternal and perinatal morbidity and mortality, especially in developing countries. The systematic review of randomized controlled trials of calcium supplementation provides promising evidence that calcium supplementation may be effective in preventing HDP in women with low calcium intake.  It is important to obtain a reliable, definitive answer to this question for both clinical and programmatic reasons.

The World Health Organization and its collaborating institutions in developing countries propose a double-blind randomized controlled trial (RCT) to evaluate the impact of calcium supplementation (1.5 g/d) started before the twentieth week of pregnancy to nulliparous women with low calcium intake, on the incidence of pre-eclampsia.  The proposed trial will enrol approximately 8500 women in seven countries over a period of 18 months.  The primary outcomes are the incidence of pre-eclampsia (hypertension and proteinuria) for women and preterm birth for newborns.  The sample size calculation is based on a reduction in the rate of pre-eclampsia from 4% in the placebo group to 2.8% in the calcium- supplemented group (30% reduction).

The UNDP/UNFPA/WHO/World Bank Special Programme  of  Research,  Development  and Research Training in Human Reproduction (HRP) of the Department of Reproductive Health and Research (RHR) at WHO will coordinate the study in collaboration with local institutions.  If the effectiveness of routine calcium supplementation  in  preventing  pre-eclampsia  is  confirmed, WHO will develop and circulate recommendations for incorporation of this practice into routine antenatal  care.    Nutritional  strategies  to  reach  the  recommended  calcium  intake  from  food sources will also be prepared and disseminated.  It is expected that if the research confirms effectiveness, implementation of this low-cost intervention will contribute to the reduction of maternal and perinatal severe morbidity and mortality due to HDP in developing countries.

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This page was last updated on 4th June 2004.