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Severity of influenza and non-influenza acute respiratory illness among pregnant women, 2010-12

Leslie Sokolow, Allison Naleway, De-Kun Li, Pat Shifflett, Sue Reynolds, Michelle Henninger, et al.


August 8, 2014

To identify characteristics of influenza illness contrasted with non-influenza acute respiratory illnesses (ARI) in pregnant women.

Study Design

ARI among pregnant women was identified through daily surveillance during two influenza seasons (2010–12). Within 8 days of illness onset, nasopharyngeal swabs were collected, and an interview was conducted for symptoms and other characteristics. A follow-up telephone interview was conducted 1–2 weeks later, and medical records were extracted. Severity of illness was evaluated by self-assessment of 12 illness symptoms, subjective ratings of overall impairment, highest reported temperature, illness duration, and medical utilization.


Of 292 pregnant women with ARI, 100 tested positive for influenza viruses. Women with influenza illnesses reported higher symptom severity than those with non-influenza ARI (median score: 18 vs. 16 out of 36; p<.05) and were more likely to report severe subjective feverishness (18% vs. 5%; p<.001), myalgia (28% vs 14%; p<.005), cough (46% vs 30%; p<.01), and chills (25% vs. 13%; p<.01). More influenza illnesses were associated with fever >38.9oC (20% vs. 5%; p<.001) and higher subjective impairment (mean score 5.9 vs. 4.8; p<.001). Differences in overall symptom severity, fever, cough, chills, early healthcare-seeking behavior, and impairment remained significant in multivariate models after adjusting for study site, season, age, vaccination status, and number of days since illness onset.


Influenza had a greater negative impact on pregnant women than non-influenza ARIs, as indicated by symptom severity and greater likelihood of elevated temperature. These results highlight the importance of preventing and treating influenza illnesses in pregnant women.