Women with moderate to severe symptoms of asthma during pregnancy are more likely to develop preeclampsia than women with no asthma symptoms, the results of a new study show.

The hallmarks of preeclampsia in pregnancy are high blood pressure and impaired kidney function, which can impair the health of both the mother and her baby.

“Our findings indicate that having a self-reported diagnosis of asthma does not increase the risk of preeclampsia; rather, it is having active asthma symptoms through pregnancy that increases the risk,” Dr. Elizabeth W. Triche from Yale University School of Medicine in New Haven, Connecticut, and colleagues explain in the medical journal Obstetrics and Gynecology.

Published studies relating asthma and preeclampsia have produced inconsistent results, “perhaps due to differences in study populations, varying definitions of asthma, and ... asthma medication use,” the investigators note in their report.

They followed 1708 pregnant women, of whom 656 had a diagnosis of asthma and 1052 did not. The team carefully accounted for asthma treatment and medication use, as well as other factors such as obesity, age, and smoking early in pregnancy.

According to the researchers, neither overall asthma severity nor having physician-diagnosed asthma were related to the odds of developing preeclampsia. However, the frequency of asthma symptoms (wheeze, persistent cough, and chest tightness) during pregnancy was tied to preeclampsia risk.

Compared with women with no asthma symptoms, women with daily symptoms were three times more likely to develop preeclampsia.

“Taken together with previous findings that actively managed asthmatics have better outcomes than untreated asthmatics, our findings suggest that patients with asthma symptoms, with or without an asthma diagnosis, should be closely monitored during their pregnancies,” Triche and colleagues conclude.

SOURCE: Obstetrics and Gynecology, September 2004.