Presentation of seasonal influenza A in pregnancy: 2003-2004 influenza season.

OBJECTIVE:To describe the clinical course of influenza in pregnant women followed at our institution during the 2003-2004 influenza season. METHODS:This was a prospective evaluation of all pregnant women diagnosed with influenza A between October 22, 2003, and January 18, 2004. Pregnant women presenting with a flu-like illness were evaluated using a rapid diagnostic test, culture, or both. Patients were admitted in accordance with prospectively developed clinical protocols. Women with a laboratory-confirmed diagnosis were treated with Centers for Disease Control-recommended antivirals. RESULTS:Influenza A was confirmed in 107 patients. All viral isolates obtained were of the H3N2 strain. Influenza was most commonly diagnosed in the third trimester (45%). Cough was the most commonly reported symptom (93%), followed by myalgias (61%), nausea or vomiting (60%), and rhinorrhea (56%). Eighty-four percent of the women had no comorbid conditions; however, 62% required admission. Twenty-one percent of patients had a maximum heart rate higher than 130 beats per minute. Complications of influenza A included pneumonia (12%), meningitis (1%), and myocarditis (1%). There were no maternal deaths. Eighty-one (76%) of the women delivered at our institution. When compared with our general obstetric population, there was no significant difference in obstetric or neonatal complications. CONCLUSION:Influenza A in pregnancy is characterized by cough, myalgia, nausea or vomiting, and rhinorrhea. Profound tachycardia disproportionate to maternal fever uniquely affected the majority of the women in our cohort. Pneumonia complicated one in eight cases; however, the anticipated excess maternal morbidities and mortality did not occur.