Association of asthma diagnosis, severity, symptoms, and treatment with risk of preeclampsia.

OBJECTIVE: Existing studies relating asthma and preeclampsia provide conflicting results, perhaps due to differences in study populations, varying definitions of asthma, and inadequate control for confounding, particularly asthma medication use. This prospective study examines associations between aspects of asthma (diagnosis, severity, symptoms, and medication use) and risk of preeclampsia.
METHODS: A total of 1,708 pregnant women, of whom 656 had asthma diagnosis and 1,052 had no asthma diagnosis, were included in this analysis. Asthma symptoms, treatment, and severity were classified according to Global Initiative for Asthma guidelines. Hospital records were abstracted, and strict criteria were applied to classify women as preeclamptic based on National Heart, Lung, and Blood Institute guidelines.
RESULTS: There were 568 of 656 women with diagnosed asthma and 353 of 1,052 women without asthma diagnosis who had symptoms or took asthma medication during pregnancy. Separate adjusted logistic regression models were run for different measures of asthma status: 1) asthma diagnosis; 2) overall Global Initiative for Asthma severity; 3) Global Initiative for Asthma symptom and treatment steps; and 4) Global Initiative for Asthma symptom step and medication type. Women at increased risk of preeclampsia were those classified as Global Initiative for Asthma symptom step 3/4 compared with no symptoms (odds ratio 3.36, 95% confidence interval 1.24-9.14) and theophylline users (odds ratio 1.16 for every dose/month increase in use, 95% confidence interval 1.02-1.33). In contrast, neither a history of physician-diagnosed asthma nor Global Initiative for Asthma treatment step was associated with preeclampsia status.
CONCLUSION: Our findings suggest that women with moderate to severe asthma symptoms, regardless of asthma diagnosis or treatment, are at increased risk of preeclampsia compared with women with no symptoms.