So says an international study published in the American Journal of Obstetrics and Gynecology.
Healthy pregnant women from Argentina, Egypt, India, Peru, South Africa, and Vietnam participated. They either took chewable calcium tablets or a similar tablet with no calcium (placebo), without knowing which type of tablet they'd gotten.
Women taking the calcium tablets were less likely to have severe complications of preeclampsia, a condition that affects some pregnant women.
The researchers included Jose Villar, MD, of the World Health Organization (WHO).
About 8,300 women joined Villar's study by their 20th week of pregnancy. Their health clinics treated patients including women falling short on calcium in their diet -- by about 50% -- during pregnancy.
The U.S. Institute of Medicine recommends that during pregnancy, calcium intake should be 1,000 to 1,300 milligrams per day from diet and supplements. The researchers gave participants chewable tablets containing 1,500 daily milligrams of calcium carbonate or a placebo that looked and tasted like the real thing.
Preeclampsia diagnoses were similar in both groups: 4.1% in the calcium group and 4.5% in the placebo group.
However, the calcium group was less likely to have severe complications from preeclampsia, the study shows. For instance:
- Risk of death for mother and baby was lower in the calcium group.
- Women taking calcium who were up to 20 years old had a lower risk of preterm delivery.
Most women took their tablets as directed, the study shows. How did calcium work? That's not clear, note Villar and colleagues.
Although they chose clinics shown to treat pregnant women with low calcium intake, the researchers didn't directly check participants' calcium consumption. It's possible that some women weren't low on calcium, Villar's team notes.