Research Article| Volume 77, ISSUE 6, P553-560, December 2018

Impact of influenza on outpatient visits and hospitalizations among pregnant women in Catalonia, Spain

  • Luz Maria Vilca
    Corresponding author.
    Department of Preventive Medicine and Epidemiology, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, 119-129 Passeig Vall d'Hebron, 08035 Barcelona, Spain
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  • Aman Verma
    Clinical & Health Informatics Research Group, Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 1140 Pine Avenue West, H3A1A3 Montreal, Canada
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  • Maurizio Bonati
    Laboratory for Mother and Child Health, Department of Public Health, IRCCS- Istituto di Ricerche Farmacologiche “Mario Negri”, Via La Masa 19, 20156 Milan, Italy
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  • Magda Campins
    Department of Preventive Medicine and Epidemiology, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, 119-129 Passeig Vall d'Hebron, 08035 Barcelona, Spain
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      • Pregnant women had higher rates of influenza-associated events than non-pregnant women.
      • Second-trimester women had the highest rates of influenza-associated outpatient visits.
      • Third-trimester women had the highest rates of influenza-associated hospitalizations.
      • Having any comorbidity was associated to an increased risk of influenza-associated events.



      To estimate outpatient visits and hospitalization rates due to cardiopulmonary illness attributable to influenza from 2008-09 to 2012-13 in a large cohort of pregnant women from Catalonia, Spain.


      We estimated the event rates occurring during influenza epidemic, influenza non-epidemic and non-influenza seasons, and by pregnancy status (one year before pregnancy, first, second and third trimester). We fitted quasi-Poisson models in order to identify the variables associated to higher event rates.


      During influenza epidemic seasons, pregnant women in their second trimester had the highest rates of outpatient visits (153 per 10,000 women-months). An increased risk of outpatient visits was associated to first or second trimester (adjusted rate ratio (aRR) = 1.17; 95% CI, 1.10–1.23 and aRR, 1.36; 95% CI, 1.28–1.43, respectively) and having any comorbidity (aRR = 1.28; 95% CI, 1.21–1.36). Women during third trimester had the highest rates of hospitalizations (1.60 per 10,000 women-months), and an increased risk of hospitalization was significantly associated to third trimester (aRR, 1.85; 95% CI, 1.01–3.39), having any comorbidity (aRR, 1.93; 95% CI, 1.10–3.41) and the pandemic influenza season (aRR, 2.90 (1.81; 95% CI, 1.81–4.64).


      Our findings provide significant information regarding influenza burden of disease among pregnant women.


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