So determined a multicenter double-blind trial of 8,325 normotensive nulliparous women, sponsored by the World Health Organization, that was reported in the March 10 issue of the American Journal of Obstetrics and Gynecology.
Half the women were randomized to a calcium supplement of 1.5 g a day throughout pregnancy while half received a placebo. The women, from populations with low dietary calcium (less than 600 mg/d), were recruited from antenatal-care clinics ranging from Argentina to Vietnam.
The primary endpoint, reducing preeclampsia, proved elusive. Calcium supplementation was associated with a non-statistically significant small reduction in preeclampsia (4.1% vs. 4.5%), said JosÃ© Villar, M.D., of the WHO here and colleagues.
However, other endpoints, though secondary, were promising. Dr. Villar reported that the rates for eclampsia (risk ratio 0.68:95%; CI 0.48-0.97) and severe gestational hypertension (risk ratio 0.71; 95%CI 0.61-0.82) were significantly lower in the calcium group.
Supplementation also brought about significant reductions in the most serious complication of preeclampsia. Overall, the researchers wrote, there was a 25% reduction in severe preeclamptic complications (risk ratio 0.76; 95% CI, 0.66-0.89). This is further reflected in the reduction in the index for severe maternal morbidity and mortality (risk ratio 0.80; 95% CI 0.70-0.9) and, finally, in a decrease in neonatal mortality (risk ratio 0.70; 95% CI, 0.56-0.88).
The causes of neonatal death for which calcium's benefits were most evident were perinatal asphyxia, preterm delivery, and neonatal infection.
In addition, for a subgroup of mothers ages 20 and younger, supplementation tended to reduce preterm and early preterm (less than 32 weeks) delivery (risk ratio, 0.82; 95% CI, 067-1.01; risk ratio, 0.64; 95% CI, 0.42-0.98, respectively). These young women, the researchers said, are known for poor dietary habits and high calcium requirements.
In conclusion, Dr. Villar said that although calcium supplementation did not lead to a statistically significant decrease in the overall rate of preeclampsia, "treatment significantly reduced the risk of its more serious complications, which included maternal and neonatal morbidity and death and preterm delivery, the latter among young women."
- Reviewed by Robert Jasmer, MD Assistant Professor of Medicine, University of California, San Francisco
American Journal of Obstetrics and Gynecology 2006:194,639-649Source Reference: Villar, JosÃ©, et al "World Health Organization randomized trial of calcium supplementation among low calcium intake women"