39. Pre-pregnancy and early pregnancy calcium supplementation in women at high risk of pre-eclampsia: a randomized, placebo controlled trial

Abstract

Reducing the death toll from hypertensive disorders of pregnancy is a global priority. Low dietary calcium may account for the high prevalence of pre-eclampsia/eclampsia in low-income countries. Calcium supplementation in the second half of pregnancy reduces the severe consequences of pre-eclampsia but the effect of calcium supplementation before and in early pregnancy, when pre-eclampsia is thought to evolve, has not been assessed. We conducted a multi-country randomised, double-blinded placebo-controlled trial to determine the effect of calcium supplementation before and in early pregnancy in sites in South Africa, Zimbabwe and Argentina over a six-year period. Participants with previous pre-eclampsia or eclampsia received 500 mg elemental calcium or placebo daily from enrolment before pregnancy until 20 weeks’ gestation. All participants received unblinded calcium 1·5 g daily after 20 weeks’ gestation. Baseline data were well matched. Almost half the women became pregnant. Pre-eclampsia was reduced by 20% with calcium (not statistically significant). Pregnancy loss and/or pre-eclampsia was reduced by 18% (borderline significance). Diastolic blood pressure was significantly reduced at both 20 and 32 weeks’ gestation. There were no other statistically significant differences. Reduced pregnancy loss and/or pre-eclampsia, and persistently lower diastolic blood pressure at 32 weeks despite high dose calcium supplementation to all participants from 20 weeks’ gestation suggests a persistent effect of calcium supplementation before and in early pregnancy on the genesis of pre-eclampsia. Public health strategies to promote adequate calcium intake may reduce pregnancy loss and/or pre-eclampsia, among many other general health benefits.