The Preeclampsia Paradox

Researchers hunt for clues why smoking cuts risk of pregnancy complication

TUESDAY, June 4, 2002 (HealthDayNews) -- Preeclampsia, a serious complication of pregnancy that causes high blood pressure, swelling and headache, is responsible for more than 75,000 deaths worldwide every year.

Scientists still don't know exactly what causes preeclampsia, but they do know that smokers, paradoxically, seem to have a lower risk of developing the disorder.

"Women who smoke have a decreased risk of preeclampsia," says Dr. Kristine Yoder Lain, lead author of a new study on the subject and an assistant professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine. "We wanted to know why it would be protective."

So, the researchers studied 63 pregnant women who did not have preeclampsia -- 26 nonsmokers, 19 women who quit smoking at the start of their pregnancy, and 18 smokers. Lain says they studied women without preeclampsia so they could see what effect tobacco was having on their health that might protect them against the condition.

The researchers measured the level of uric acid, a byproduct of metabolizing protein, in the women's blood. They found elevated levels of uric acid in the smokers, but the women who had the highest concentrations of uric acid were women who had quit smoking at the start of their pregnancies. Lain suggests these findings may point to the reason smokers have lower rates of preeclampsia. However, she stopped short of saying that smoking may help hold down levels of uric acid.

Dr. Boris Petrikovsky, chairman of the department of obstetrics and gynecology at Nassau University Medical Center in East Meadow, N.Y., says high levels of uric acid are also seen in women with preeclampsia.

"There are various mechanisms that can elevate uric acid levels," Petrikovsky says. "In preeclampsia, it's most likely because of some problem with the kidneys' ability to filter. In smoking, there may be different mechanisms [at work]. This study doesn't necessarily link them to each other."

However, he says the Pittsburgh research should encourage further studies because if scientists can determine how smoking is protective, they may learn a cause of preeclampsia or come up with a way to treat it.

Despite the evidence that tobacco might help ward off preclampsia, both doctors strongly caution pregnant women not to smoke.

"We should not promote smoking to decrease preeclampsia," Petrikovsky says. "There is evidence that smoking is clearly detrimental to the health of the mother and the baby."

Lain adds that smoking has been shown to increase the risk of low birth weight, miscarriage and early delivery.

She presented her findings today at the 13th World Congress of the International Society for the Study of Hypertension in Pregnancy in Toronto.

Lain also presented the findings of another preeclampsia study she and her colleagues conducted. This one included one group of 5,000 women who had two separate, healthy pregnancies and another group of 120 women who developed preeclampsia during their first pregnancy, but not their second.

The researchers found that women who developed preeclampsia early in their first pregnancy were at greater risk of delivering their babies prematurely, even though they didn't develop preeclampsia during the second pregnancy.

What To Do

For more information on preeclampsia, visit the Preeclampsia Foundation or Baby Center.

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