Objective: The aim of this study was to present results of the post-pandemic phase of A(H1N1)pdm09 virus infection in pregnant women in Ceará, Brazil, during the January-June 2012 influenza season.
Results: One hundred and fifty-four nasopharyngeal swab samples were collected from pregnant women admitted to hospitals with suspected severe acute respiratory infection (SARI). Fifty-three (34.4%) had laboratory-confirmed A(H1N1)pdm09 virus infection with 15 (28.3%) outpatients and 38 (71.7%) hospitalized. Five (9.4%) women were in the first trimester of pregnancy, 20 (37.7%) in the second trimester of pregnancy, and 24 (45.2%) in the third trimester of pregnancy. Three had no information about the time of pregnancy. Six samples from newborns were also analyzed, of which three were nasopharyngeal swab-positive for A(H1N1)pdm09. These swabs were collected immediately after birth, with the exception of one that was collected on the day after birth.
Conclusion: Our findings suggest that transplacental transfer of influenza viruses could occur as a result of severe illness in pregnancy. It is therefore important to encourage women to be vaccinated against influenza in order to avoid pregnancy complications.