Effect of calcium supplementation on pregnancy-induced hypertension and preeclampsia: a meta-analysis of randomized controlled trials.
OBJECTIVE
To review the effect of calcium supplementation during pregnancy on blood pressure, preeclampsia, and adverse outcomes of pregnancy.


METHODS
We searched MEDLINE and EMBASE for 1966 to May 1994. We contacted authors of eligible trials to ensure accuracy and completeness of data and to identify unpublished trials.


METHODS
Fourteen randomized trials involving 2459 women were eligible.


METHODS
Reviewers working independently in pairs abstracted data and assessed validity according to six quality criteria.


RESULTS
Each trial yielded differences in blood pressure change between calcium supplementation and control groups that we weighted by the inverse of the variance. The pooled analysis showed a reduction in systolic blood pressure of -5.40 mm Hg (95% confidence interval [CI], -7.81 to -3.00 mm Hg; P<.001) and in diastolic blood pressure of -3.44 mm Hg (95% CI, -5.20 to -1.68 mm Hg; P<.001). The odds ratio for preeclampsia in women with calcium supplementation compared with placebo was 0.38 (95% CI, 0.22 to 0.65).


CONCLUSIONS
Calcium supplementation during pregnancy leads to an important reduction in systolic and diastolic blood pressure and preeclampsia. While pregnant women at risk of preeclampsia should consider taking calcium, many more patient events are needed to confirm calcium's impact on maternal and fetal morbidity.
Bucher
H C
HC
Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
Guyatt
G H
GH
Cook
R J
RJ
Hatala
R
R
Cook
D J
DJ
Lang
J D
JD
Hunt
D
D
D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000008:administration & dosage / Q000494:pharmacology*; D003971:Diastole / Q000187:drug effects; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000517:prevention & control*; D011225:Pre-Eclampsia / Q000453:epidemiology / Q000517:prevention & control*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology / Q000517:prevention & control*; D011256:Pregnancy Outcome; D016032:Randomized Controlled Trials as Topic; D013599:Systole / Q000187:drug effects
D002118:Calcium