The effect of calcium supplementation on blood pressure in non-pregnant women with previous pre-eclampsia: An exploratory, randomized placebo controlled study

Background Epidemiological findings suggest that the link between poverty and pre-eclampsia might be dietary calcium deficiency. Calcium supplementation has been associated with a modest reduction in pre-eclampsia, and also in blood pressure (BP). Methods This exploratory sub-study of the WHO Calcium and Pre-eclampsia (CAP) trial aims to determine the effect of 500 mg/day elemental calcium on the blood pressure of non-pregnant women with previous pre-eclampsia. Non-pregnant women with at least one subsequent follow-up trial visit at approximately 12 or 24 weeks after randomization were included. Results Of 836 women randomized by 9 September 2014, 1st visit data were available in 367 women of whom 217 had previously had severe pre-eclampsia, 2nd visit data were available in 201 women. There was an overall trend to reduced BP in the calcium supplementation group (1-2.5 mmHg) although differences were small and not statistically significant. In the subgroup with previous severe pre-eclampsia, the mean diastolic BP change in the calcium group (-2.6 mmHg) was statistically larger than in the placebo group (+0.8 mmHg), (mean difference -3.4, 95% CI -0.4 to -6.4; p = 0.025). The effect of calcium on diastolic BP at 12 weeks was greater than in those with non-severe pre-eclampsia (p = 0.020, ANOVA analysis). Conclusions There is an overall trend to reduced BP but only statistically significant in the diastolic BP of women with previous severe pre-eclampsia. This is consistent with our hypothesis that this group is more sensitive to calcium supplementation, however results need to be interpreted with caution.Fil: Hofmeyr, G. J.. University of the Witwatersrand; SudáfricaFil: Seuc, A. H.. World Health Organization; SuizaFil: Betrán, A. P.. World Health Organization; SuizaFil: Purnat, T. D.. World Health Organization; DinamarcaFil: Ciganda, Álvaro. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Munjanja, S. P.. University of Zimbabwe; ZimbabueFil: Manyame, S.. University of Zimbabwe; ZimbabueFil: Singata, M.. Fort Hare University; SudáfricaFil: Fawcus, S.. University of Cape Town; Sudáfrica. Mowbray Maternity Hospital; SudáfricaFil: Frank, K.. University of the Witwatersrand; SudáfricaFil: Hall, D. R.. Stellenbosch University; Sudáfrica. Tygerberg Hospital; SudáfricaFil: Cormick, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Roberts, J. M.. University of Pittsburgh; Estados UnidosFil: Bergel, Eduardo F.. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Drebit, S.K.. University of British Columbia; CanadáFil: von Dadelszen, P.. University of British Columbia; CanadáFil: Belizan, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Calcium and Pre-eclampsia Study Group. No especifica