FRIDAY, March 10, 2006 (HealthDay News) -- Boosting the calcium intake of pregnant women with low dietary calcium can help prevent complications from a dangerous condition known as preeclampsia, in which a woman's blood pressure rises dramatically, a new global study found.
However, the extra calcium did not significantly reduce the number of women who got preeclampsia, according to Dr. Jose Villar of the World Health Organization, lead author of the study that appears in the March issue of the American Journal of Obstetrics & Gynecology.
"It was not as positive as one would like," Dr. Marshall Lindheimer, professor emeritus of medicine and obstetrics and gynecology at the University of Chicago, said of the calcium-preeclampsia prevention link. He is a co-author on the study.
The 1.5 gram calcium supplement taken daily by women in the study "didn't prevent the disease, all it did was to decrease the severity," Lindheimer said. But it did decrease the rate of maternal and newborn deaths, he said.
Preeclampsia affects about 9 percent of pregnancies worldwide, according to Villar. It can lead to premature delivery and the need for a Caesarean section. If it progresses to a more serious condition, eclampsia, the woman can suffer seizures or coma. In the worst cases, preeclampsia can cause disability or death of mother or fetus.
In the study, Villar and his team assigned more than 8,300 women who were receiving health care from one of eight centers in six countries to either the calcium-supplementation group or a placebo group. Before the study, all the women took in less than 600 milligrams a day of dietary calcium, or about half the amount recommended during pregnancy.
When the researchers followed up, they found the rate of preeclampsia was not statistically different between the groups. But eclampsia was lower in those treated, with 17 women in the calcium group stricken with eclampsia compared to 25 in the placebo group. Severe gestational high blood pressure was higher in the placebo group, too, with 59 of the women developing hypertension vs. 43 in the calcium-treated group.
Newborn death was also less likely in the supplementation group, with 0.9 percent infant deaths in the calcium group compared to 1.3 percent in the placebo group.
Finally, the risk of early preterm delivery -- before 32 weeks -- was 2.6 percent in the calcium group, but 3.2 percent in the placebo group.
Women in the study received health care at centers in Argentina, Egypt, India, Peru, South Africa and Vietnam. Each center is part of the World Health Organization's Maternal and Perinatal Research Network.
The cause of preeclampsia is still unknown, and there's no way to prevent it. A relationship between calcium deficiency and preeclampsia has long been suspected.
Lindheimer said it's not clear how calcium may help. "It may affect the contractability of the blood vessels," he said. "Intracellular calcium is very important in muscle physiology." Insufficient calcium consumption may lead to more constriction of the vessels, he said. "When you replenish the calcium, they [vessels] are in a more dilated state. It may be that effect which makes the disease less severe."
The study results are of greatest value mostly outside the United States, Lindheimer said, where calcium deficiency is a bigger problem.
But the study might also serve as a useful reminder for U.S. doctors to urge their pregnant patients to get enough calcium, he said.
While the study results don't necessarily apply to American women, the findings are interesting, said Dr. Ashley Roman, an assistant professor of obstetrics and gynecology at the New York University School of Medicine.
"It helps us to understand the process of preeclampsia better," she said. "When it comes to preeclampsia, we are still in the dark ages. We have been studying it for years, and we don't know what causes it, how to predict it well, and we really don't know how to prevent it."
Roman tells her pregnant patients to be sure to take in 1,200 milligrams of calcium daily, if not from diet, then from a calcium supplement.
For more on pregnancy and nutrition, visit the Nemours Foundation.