THURSDAY, Oct. 18, 2001 (HealthDayNews) -- Here's more evidence that Mother Nature knows best: Popping calcium pills won't protect a pregnant woman from a dangerous form of high blood pressure, but eating calcium-rich foods just may, says a new study.
This adds another voice to the chorus of studies that show that calcium supplements fall short as a treatment for preeclampsia, a life-threatening rise in blood pressure that can occur in the third trimester of pregnancy. The research was presented at the recent annual meeting of the Council for High Blood Pressure Research in Chicago.
"We can add our research to the growing body of data indicating that women who have chronic hypertension before pregnancy will not reduce their risk of blood pressure-related complications during pregnancy simply by taking calcium supplements," says the study's author, Dr. Phyllis August. She is head of the division of hypertension at New York Weill Cornell Medical Center.
Although women who do not have chronic hypertension can develop preeclampsia, August says women whose pressure is already high going into the pregnancy have a much higher risk of the condition.
"This is one of the reasons it's so important to get blood pressure under control before you conceive," says August.
The notion that calcium supplements might help dates back a number of years, when theories first suggested it might have a positive effect on blood vessels, which in turn might affect pressure.
"Unfortunately, the idea that calcium could reduce the risk of preeclampsia was never really supported -- and it seems this study now seals the fate on calcium. It doesn't work," says Dr. Michael Silverstein, professor of obstetrics and gynecology at New York University Medical Center.
However, for a small number of women within the study, an increase in dietary calcium appeared to have some protective effects. Researchers say they can't account for the finding.
But Silverstein questions any conclusions you might draw from this finding.
"This was a relatively small study, and the problem here is that there was poor compliance with the dietary record, so I'm not really sure it was looked at properly," he says.
The study involved 116 women, all of whom had been diagnosed with chronic high blood pressure before becoming pregnant. Beginning in their 13th week of pregnancy, half the group women took calcium supplements in amounts of 2 grams per day, while the other half took a placebo.
By the end of the pregnancies, almost 28 percent of the women developed preeclampsia, and another 7 percent developed a rapid rise in blood pressure with indications of preeclampsia.
"When the two conditions were combined, the women in both groups -- those taking the calcium supplements and those taking placebo -- had nearly identical risks of preeclampsia," says August. To help insure the accuracy of the findings, the study controlled for both race and number of previous children -- factors that could have affected the outcome.
The researchers did point out that dietary records for the three days before the study started showed that women who had a low intake of calcium-rich foods went on to develop preeclampsia, while those with a higher intake had a reduced risk. Unfortunately, only one-third of the women in the study were able to recall their pre-entry diet, so statistically the findings remain incomplete.
Risk factors for preeclampsia that did come to light in the study include systolic blood pressure (when the heart contracts) greater than 140 at the 20th week of pregnancy, and a previous history of preeclampsia in another pregnancy.
Also making a difference, says August, were higher than normal levels of three body chemicals at the 20 week mark: uric acid, parathyroid hormone and cellular levels of calcium.
What To Do
Although calcium supplements may not help you avoid preeclampsia, doctors remind you that they continue to play an important role in helping women meet their calcium requirement during pregnancy -- which is about 1,500 mg a day.
"I tell my patients they need five servings of calcium a day -- about 300 mg per serving," says Silverstein. Getting calcium from low-fat dairy sources is important, he says, but when you can't consume enough, calcium supplements can be very helpful.
To learn more about high blood pressure and pregnancy, visit the Preeclampsia Foundation found here.
To learn more about the health benefits of calcium including the best dietary sources, click here.
For more information on calcium supplements, click
here. For more about treatments for high blood pressure, click here.
