title: The effect of calcium supplementation on blood pressure in non-pregnant women with previous pre-eclampsia: An exploratory, randomized placebo controlled study.
abstract: 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 500mg/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 24weeks 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 (1-2.5mmHg) 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 (-2.6mmHg) was statistically larger than in the placebo group (+0.8mmHg), (mean difference -3.4, 95% CI -0.4 to -6.4; p=0.025). The effect of calcium on diastolic BP at 12weeks 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.
authors.affiliation: Department of Obstetrics and Gynaecology, East London Hospital Complex, University of the Witwatersrand, South Africa; University of Fort Hare, Eastern Cape Department of Health, East London, South Africa. Electronic address: justhof@gmail.com.
authors.forename: G J
authors.initials: GJ
authors.lastname: Hofmeyr
authors.affiliation: Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland. Electronic address: seuca@who.int.
authors.forename: A H
authors.initials: AH
authors.lastname: Seuc
authors.affiliation: Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland. Electronic address: betrana@who.int.
authors.forename: A P
authors.initials: AP
authors.lastname: Betrán
authors.affiliation: World Health Organization Regional Office for Europe, Marmorvej 51, Copenhagen, Denmark. Electronic address: tina.purnat@gmail.com.
authors.forename: T D
authors.initials: TD
authors.lastname: Purnat
authors.affiliation: Institute for Clinical Effectiveness and Health Policy (IECS), Emilio Ravignani 2024, Buenos Aires, Argentina. Electronic address: alvaro@ciganda.com.
authors.forename: A
authors.initials: A
authors.lastname: Ciganda
authors.affiliation: University of Zimbabwe, Harare, Zimbabwe. Electronic address: spmunjanja@gmail.com.
authors.forename: S P
authors.initials: SP
authors.lastname: Munjanja
authors.affiliation: University of Zimbabwe, Harare, Zimbabwe. Electronic address: smanyame79@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Manyame
authors.affiliation: Department of Nursing Sciences, Fort Hare University, South Africa. Electronic address: mandisa.singata@gmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Singata
authors.affiliation: Department of Obstetrics and Gynaecology, University of Cape Town, South Africa; Head, Obstetric Services, Mowbray Maternity Hospital, Cape Town, South Africa. Electronic address: fawcus@mweb.co.za.
authors.forename: S
authors.initials: S
authors.lastname: Fawcus
authors.affiliation: Department of Obstetrics and Gynaecology, University of the Witwatersrand, South Africa. Electronic address: kafrank@mweb.co.za.
authors.forename: K
authors.initials: K
authors.lastname: Frank
authors.affiliation: Department of Obstetrics and Gynaecology, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa. Electronic address: drh@sun.ac.za.
authors.forename: D R
authors.initials: DR
authors.lastname: Hall
authors.affiliation: Institute for Clinical Effectiveness and Health Policy (IECS), Emilio Ravignani 2024, Buenos Aires, Argentina. Electronic address: gcormick@iecs.org.ar.
authors.forename: G
authors.initials: G
authors.lastname: Cormick
authors.affiliation: Magee-Womens Research Institute, Department of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, USA. Electronic address: jroberts@mwri.magee.edu.
authors.forename: J M
authors.initials: JM
authors.lastname: Roberts
authors.affiliation: Institute for Clinical Effectiveness and Health Policy (IECS), Emilio Ravignani 2024, Buenos Aires, Argentina. Electronic address: bergel@gmail.com.
authors.forename: E F
authors.initials: EF
authors.lastname: Bergel
authors.affiliation: Department of Obstetrics and Gynaecology, University of British Columbia, Room V3-339, 950 West 28th Avenue, Vancouver, BC V5Z 4H4, Canada. Electronic address: Sharla.Drebit@phsa.ca.
authors.forename: S K
authors.initials: SK
authors.lastname: Drebit
authors.affiliation: Department of Obstetrics and Gynaecology, University of British Columbia, Room V3-339, 950 West 28th Avenue, Vancouver, BC V5Z 4H4, Canada. Electronic address: pvd@cw.bc.ca.
authors.forename: P
authors.initials: P
authors.lastname: Von Dadelszen
authors.affiliation: Institute for Clinical Effectiveness and Health Policy (IECS), Emilio Ravignani 2024, Buenos Aires, Argentina. Electronic address: belizanj@gmail.com.
authors.forename: J M
authors.initials: JM
authors.lastname: Belizan
mesh_terms: D000328:Adult; D001118:Argentina; D001794:Blood Pressure / Q000187:drug effects*; D001795:Blood Pressure Determination / Q000379:methods; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D011225:Pre-Eclampsia / Q000517:prevention & control*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000517:prevention & control*; D018570:Risk Assessment; D013019:South Africa; D016896:Treatment Outcome; D014944:World Health Organization; D015030:Zimbabwe
chemical_list: D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary
keywords: Blood Pressure; Calcium; Hypertension; Preeclampsia; Supplementation