G J Hofmeyr1, A N Atallah, L Duley. 1. University of the Witwatersrand, University of Fort Hare, Eastern Cape Department of Health, Frere and Cecilia Makiwane Hospitals, Private Bag X 9047, East London, Eastern Cape, South Africa 5200. gjh@global.co.za
Abstract
BACKGROUND: Pre-eclampsia and eclampsia are common causes of serious morbidity and death. Calcium supplementation may reduce the risk of pre-eclampsia through a number of mechanisms, and may help to prevent preterm labour. OBJECTIVES: To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child outcomes. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (February 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2005, Issue 4), and contacted study authors. SELECTION CRITERIA: Randomised trials comparing at least one gram daily of calcium during pregnancy with placebo. DATA COLLECTION AND ANALYSIS: We assessed eligibility and trial quality, extracted and double-entered data. MAIN RESULTS: Twelve studies of good quality were included. The risk of high blood pressure was reduced with calcium supplementation rather than placebo (11 trials, 14,946 women: relative risk (RR) 0.70, 95% confidence interval (CI) 0.57 to 0.86). There was also a reduction in the risk of pre-eclampsia associated with calcium supplementation (12 trials, 15,206 women: RR 0.48, 95% CI 0.33 to 0.69). The effect was greatest for high-risk women (5 trials, 587 women: RR 0.22, 95% CI 0.12 to 0.42), and those with low baseline calcium intake (7 trials, 10,154 women: RR 0.36, 95% CI 0.18 to 0.70). The composite outcome maternal death or serious morbidity was reduced (4 trials, 9732 women; RR 0.80, 0.65 to 0.97). Almost all the women in these trials were low risk and had a low calcium diet. Maternal deaths were reported in only one trial. One death occurred in the calcium group and six in the placebo group, a difference which was not statistically significant (RR 0.17, 95% CI 0.02 to 1.39). There was no overall effect on the risk of preterm birth (10 trials, 14,751 women: RR 0.81, 95% CI 0.64 to 1.03), or stillbirth or death before discharge from hospital (10 trials 15,141 babies; RR 0.89, 95% CI 0.73 to 1.09).Blood pressure in childhood has been assessed in one study: childhood systolic blood pressure greater than 95th percentile was reduced (514 children: RR 0.59, 95% CI 0.39 to 0.91). AUTHORS' CONCLUSIONS: Calcium supplementation appears to almost halve the risk of pre-eclampsia, and to reduce the rare occurrence of the composite outcome 'death or serious morbidity'. There were no other clear benefits, or harms.
BACKGROUND: Pre-eclampsia and eclampsia are common causes of serious morbidity and death. Calcium supplementation may reduce the risk of pre-eclampsia through a number of mechanisms, and may help to prevent preterm labour. OBJECTIVES: To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child outcomes. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (February 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2005, Issue 4), and contacted study authors. SELECTION CRITERIA: Randomised trials comparing at least one gram daily of calcium during pregnancy with placebo. DATA COLLECTION AND ANALYSIS: We assessed eligibility and trial quality, extracted and double-entered data. MAIN RESULTS: Twelve studies of good quality were included. The risk of high blood pressure was reduced with calcium supplementation rather than placebo (11 trials, 14,946 women: relative risk (RR) 0.70, 95% confidence interval (CI) 0.57 to 0.86). There was also a reduction in the risk of pre-eclampsia associated with calcium supplementation (12 trials, 15,206 women: RR 0.48, 95% CI 0.33 to 0.69). The effect was greatest for high-risk women (5 trials, 587 women: RR 0.22, 95% CI 0.12 to 0.42), and those with low baseline calcium intake (7 trials, 10,154 women: RR 0.36, 95% CI 0.18 to 0.70). The composite outcome maternal death or serious morbidity was reduced (4 trials, 9732 women; RR 0.80, 0.65 to 0.97). Almost all the women in these trials were low risk and had a low calcium diet. Maternal deaths were reported in only one trial. One death occurred in the calcium group and six in the placebo group, a difference which was not statistically significant (RR 0.17, 95% CI 0.02 to 1.39). There was no overall effect on the risk of preterm birth (10 trials, 14,751 women: RR 0.81, 95% CI 0.64 to 1.03), or stillbirth or death before discharge from hospital (10 trials 15,141 babies; RR 0.89, 95% CI 0.73 to 1.09).Blood pressure in childhood has been assessed in one study: childhood systolic blood pressure greater than 95th percentile was reduced (514 children: RR 0.59, 95% CI 0.39 to 0.91). AUTHORS' CONCLUSIONS: Calcium supplementation appears to almost halve the risk of pre-eclampsia, and to reduce the rare occurrence of the composite outcome 'death or serious morbidity'. There were no other clear benefits, or harms.
Authors: Eileen R Fowles; Miranda Bryant; SungHun Kim; Lorraine O Walker; Roberta Jeanne Ruiz; Gayle M Timmerman; Adama Brown Journal: Nurs Res Date: 2011 Sep-Oct Impact factor: 2.381
Authors: Fernando C Barros; Zulfiqar Ahmed Bhutta; Maneesh Batra; Thomas N Hansen; Cesar G Victora; Craig E Rubens Journal: BMC Pregnancy Childbirth Date: 2010-02-23 Impact factor: 3.007
Authors: Esme V Menezes; Mohammad Yawar Yakoob; Tanya Soomro; Rachel A Haws; Gary L Darmstadt; Zulfiqar A Bhutta Journal: BMC Pregnancy Childbirth Date: 2009-05-07 Impact factor: 3.007
Authors: Anne Merewood; Supriya D Mehta; Tai C Chen; Howard Bauchner; Michael F Holick Journal: J Clin Endocrinol Metab Date: 2008-12-23 Impact factor: 5.958
Authors: Rachel Bakker; Sheryl L Rifas-Shiman; Ken P Kleinman; Steven E Lipshultz; Matthew W Gillman Journal: Am J Epidemiol Date: 2008-10-22 Impact factor: 4.897