Objective Prostaglandin E2 is a pharmacologic agent that is used comm only in o bstetrics; however, its usage in patients with asthma is unclear. The study obje ctive was to examine pregnant patients with asthma who received prostaglandin E2 . Study design All pregnancies that were given prostaglandin E2 suppositories an d/or gel were recorded prospectively from January 1989 through December 2000. Th ose cases with a history of asthma or active asthma were analyzed for any clinic al evidence of disease exacerbation after the administration of the agent. Clini cal exacerbation was defined as any respiratory complaint that followed drug usa ge, the initiation of bronchodilator medications by patients currently not on th erapy, or an increase in bronchodilator usage by patients with active disease. R esults During the study period, 2513 patients received treatment with the cervic al ripening gel, of whom 158 patients had a history of asthma or active asthma. Additionally, 536 patients were administered the 20-mg suppositories, of whom 3 1 patients had a history of asthma or active asthma. Thus, a total of 189 patien ts with a history of asthma or active asthma were exposed to prostaglandin E2, a nd none of the patients had any evidence of a clinical exacerbation of the disea se (0/189 cases; 95%CI, 0-2%). Conclusion Based on the 95%CI of these data, the maximum risk for the development of a clinical exacerbation of asthma, if ex posed to the obstetric forms of prostaglandin E2, is ≤2%. Although all drug us age in patients with asthma should be monitored carefully, this information woul d support the usage of prostaglandin E2, if obstetrically indicated, in pregnant patients with asthma. Objective, which is used in commits only only o o bstetrics; however, its usage in patients with asthma is unclear. The study obje ctive was to examine pregnant patients with asthma who received prostaglandin E2. Study design All pregnancies that the given prostaglandin E2 suppositories an d / or gel were recorded prospectively from January 1989 through December 2000. Those cases with a history of asthma or active asthma were analyzed for any clinic al evidence of disease exacerbation after the administration of the agent. Clini cal exacerbation was defined as any respiratory complaint that followed drug usa, the initiation of bronchodilator medications by patients currently not on th erapy, or an increase in bronchodilator usage by patients with active disease. Résults During the study period, 2513 patients received treatment with the cervic al ripening gel, of whom 158 patients had a history of asthma or active asthma. Additionally, 536 patients wer of a patient of a history of asthma or active asthma. Thus, a total of 189 patien ts with a history of asthma or active asthma were exposed to prostaglandin E2, a nd none of the patients had any evidence of a clinical exacerbation of the disea se (0/189 cases; 95% CI, 0-2%). Conclusion Based on the 95% CI of these data, the maximum risk for the development of a clinical exacerbation of asthma , if exposed to the obstetric forms of prostaglandin E2, is ≤ 2%. Although all drug us age in patients with asthma should be monitored carefully, this information woul d support the usage of prostaglandin E2, if obstetrically indicated, in pregnant patients with asthma.