Prepregnancy and early pregnancy calcium supplementation among women at high risk of pre-eclampsia: a multicentre, double-blind, randomised, placebo-controlled trial
Authors: G Justus Hofmeyr, Ana Pilar Betrán, Mandisa Singata-Madliki, Gabriela Cormick, Stephen P Munjanja, Susan Fawcus, Simpiwe Mose, David Hall, Alvaro Ciganda, Armando H Seuc, Theresa A Lawrie, Eduardo Bergel, James M Roberts, Peter von Dadelszen, José M Belizán, Fernando Althabe, José M Belizán, Eduardo Bergel, Alvaro Ciganda, Gabriela Cormick, Diane Sawchuck, Marianne Vidler, Saadiqa Allie, John Anthony, Karlyn Frank, Annmarie de Greeff, Sue Fawcus, David Hall, Justus Hofmeyr, Mvuseleli Kovane, Patience Kovane, Theresa Lawrie, Simpiwe Mose, Nolundi Mshweshwe, Velisa Mqikela, Pamela Njikelana, Natalia Novikova, Adegboyega Oyebajo, Catherine Parker, Angel Phuti, Mandisa Singata-Madliki, Erika van Papendorp, Xoliswa Williams, Ana Pilar Betrán, Tina Dannemann, Armando Seuc, Laura Magee, Peter von Dadelszen, France Donnay, Sharla Drebit, Jim Roberts, Bothwell Guzha, Emilia Makaza, Sarah Manyame, Stephen Munjanja, Eunice Tahuringana
Journal: The Lancet (2019)

BackgroundReducing deaths from hypertensive disorders of pregnancy is a global priority. Low dietary calcium might account for the high prevalence of pre-eclampsia and eclampsia in low-income countries. Calcium supplementation in the second half of pregnancy is known to reduce the serious consequences of pre-eclampsia; however, the effect of calcium supplementation during placentation is not known. We aimed to test the hypothesis that calcium supplementation before and in early pregnancy (up to 20 weeks' gestation) prevents the development of pre-eclampsiaMethodsWe did a multicountry, parallel arm, double-blind, randomised, placebo-controlled trial in South Africa, Zimbabwe, and Argentina. Participants with previous pre-eclampsia and eclampsia received 500 mg calcium or placebo daily from enrolment prepregnancy until 20 weeks' gestation. Participants were parous women whose most recent pregnancy had been complicated by pre-eclampsia or eclampsia and who were intending to become pregnant. All participants received unblinded calcium 1·5 g daily after 20 weeks' gestation. The allocation sequence (1:1 ratio) used computer-generated random numbers in balanced blocks of variable size. The primary outcome was pre-eclampsia, defined as gestational hypertension and proteinuria. The trial is registered with the Pan-African Clinical Trials Registry, number PACTR201105000267371. The trial closed on Oct 31, 2017.FindingsBetween July 12, 2011, and Sept 8, 2016, we randomly allocated 1355 women to receive calcium or placebo; 331 of 678 participants in the calcium group versus 320 of 677 in the placebo group became pregnant, and 298 of 678 versus 283 of 677 had pregnancies beyond 20 weeks' gestation. Pre-eclampsia occurred in 69 (23%) of 296 participants in the calcium group versus 82 (29%) of 283 participants in the placebo group with pregnancies beyond 20 weeks' gestation (risk ratio [RR] 0·80, 95% CI 0·61–1·06; p=0·121). For participants with compliance of more than 80% from the last visit before pregnancy to 20 weeks' gestation, the pre-eclampsia risk was 30 (21%) of 144 versus 47 (32%) of 149 (RR 0·66, CI 0·44–0·98; p=0·037). There were no serious adverse effects of calcium reported.InterpretationCalcium supplementation that commenced before pregnancy until 20 weeks' gestation, compared with placebo, did not show a significant reduction in recurrent pre-eclampsia. As the trial was powered to detect a large effect size, we cannot rule out a small to moderate effect of this intervention.FundingThe University of British Columbia, a grantee of the Bill & Melinda Gates Foundation; UNDP–UNFPA–UNICEF–WHO–World Bank Special Programme of Research, Development and Research Training in Human Reproduction, WHO; the Argentina Fund for Horizontal Cooperation of the Argentinean Ministry of Foreign Affairs; and the Centre for Intervention Science in Maternal and Child Health.