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Calcium Supplementation during Pregnancy in Reducing Risk of Gestational Hypertensive Disorders

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More Intervention Effect Estimate Summaries

Imdad A, Jabeen A, Bhutta ZA. Role of calcium supplementation during pregnancy in reducing risk of developing gestational hypertensive disorders: a meta-analysis of studies from developing countries. BMC Public Health. 2011; 11 (Suppl 3): S18.


  • Hypertension in pregnancy stand alone or with proteinuria is one of the leading causes of maternal mortality and morbidity in the world (1).  Hypertensive disorders are the second most common cause of maternal deaths worldwide (2) and account for more than 40,000 maternal deaths annually (3).  These disorders are also associated with adverse perinatal outcomes such as stillbirth, preterm and small for gestational age (SGA) babies (4-6).
  • There is substantial data that supports that calcium supplementation in pregnancy is associated with reduction in gestational hypertensive disorder (7, 8), although the impact varies according to the baseline calcium intake of the population and pre-existing risk factors (9, 10).

Intervention Effects

Calcium Supplementation on Maternal Mortality

  • One study (11) reported a cumulative outcome for severe maternal morbidity/mortality which included all the severe morbidities related to maternal hypertensive disorders that can lead to maternal death.
  • 20% reduction in maternal morbidity/mortality (RR: 0.80; 95% CI 0.70-0.91) - moderate quality of evidence (however, it is downgraded to “low” to translate it to maternal mortality.

Calcium Supplementation during Pregnancy on Gestational Hypertension

  • 45% reduction in risk of gestational hypertension (RR: 0.55; 95% CI 0.36-0.85)  - 6 studies (high quality)

Calcium Supplementation during Pregnancy on Pre-eclampsia

  • 59% reduction in risk of pre-eclampsia (RR: 0.41; 95% CI 0.24-0.69) – high quality of evidence
  • The reduction was more marked in participants with a higher pre-pregnancy risk of developing gestational hypertensive disorders (RR: 0.18; 95% CI 0.07-0.42) compared to that of low risk women (RR: 0.51; 95% CI 0.30-0.87)

Calcium Supplementation during Pregnancy on Neonatal Mortality

  • 30% reduction in all-cause neonatal mortality (RR:  0.70; 95% CI 0.56-0.88) – 1 study (low quality)

Calcium Supplementation during Pregnancy on Neonatal Outcomes

  • 12% reduction in risk of pre-term birth (RR: 0.88; 95% CI 0.78-0.99)- 5 studies – high quality of evidence
  • No impact of risk of low birth weight (RR: 0.81; 95% CI 0.58-1.12)– 3 studies (moderate quality)
  • Non-significant reduction in risk for SGA (RR: 0.80; 95% CI 0.59-1.38) – 2 studies (moderate quality)

Intervention Recommendation

  • Calcium should be supplemented to all women during pregnancy in developing countries.
  • 20% reduction in maternal mortality is based on risk reduction in gestational hypertensive related severe morbidity/mortality (RR: 0.80; 95% CI 0.70-0.91)
  • 30% reduction in neonatal mortality is based on risk reduction in all-cause neonatal mortality (RR:  0.70; 95% CI 0.56-0.88)

References from Imdad Paper Cited Here

  1. Duley L. The global impact of pre-eclampsia and eclampsia. Semin Perinatol. 2009;33(3):130–137.
  2. Khan KS, Wojdyla D, Say L, Gulmezoglu AM, Van Look PF. WHO analysis of causes of maternal death: a systematic review. Lancet. 2006;367(9516):1066–1074. 
  3. Villar J, Say L, Shennan A, Lindheimer M, Duley L, Conde-Agudelo A. Methodological and technical issues related to the diagnosis, screening, prevention and treatment of pre-eclampsia and eclampsia. International Journal of Gynecology & Obstetrics. 2004;85(Suppl 1):S28–S41.
  4. Villar J, Belizan J, Fisher P. Epidemiological observation on the relationship between calcium intake and eclampsia. Int J Gynaecol Obstet. 1983;21:271. 
  5. Habli M, Levine RJ, Qian C, Sibai B. Neonatal outcomes in pregnancies with preeclampsia or gestational hypertension and in normotensive pregnancies that delivered at 35, 36, or 37 weeks of gestation. Am J Obstet Gynecol. 2007;197(4):406 e401–407. 
  6. Ananth CV, Basso O. Impact of pregnancy-induced hypertension on stillbirth and neonatal mortality. Epidemiology. 2010;21(1):118–123. 
  7. Bucher HC, Cook RJ, Guyatt GH, Lang JD, Cook DJ, Hatala R, Hunt DL. Effects of dietary calcium supplementation on blood pressure. A meta-analysis of randomized controlled trials. Jama. 1996;275(13):1016–1022. 
  8. Hofmeyr GJ, Atallah AN, Duley L. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database Syst Rev. 2006;3:CD001059.
  9. Hofmeyr GJ, Duley L, Atallah A. Dietary calcium supplementation for prevention of pre-eclampsia and related problems: a systematic review and commentary. Bjog. 2007;114(8):933–943.
  10. Trumbo PR, Ellwood KC. Supplemental calcium and risk reduction of hypertension, pregnancy-induced hypertension, and preeclampsia: an evidence-based review by the US Food and Drug Administration. Nutr Rev. 2007;65(2):78–87
  11. Villar J, Abdel-Aleem H, Merialdi M, Mathai M, Ali MM, Zavaleta N, Purwar M, Hofmeyr J, Nguyen TN, Campodonico L, et al: World Health Organization randomized trial of calcium supplementation among low calcium intake pregnant women. Am J Obstet Gynecol 2006, 194(3): 639-649.

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