The study included all pregnant women who consulted for ILI or isolated fever after clinical and laboratory investigations and had a molecular diagnostic assay for influenza during two time periods, both during influenza epidemics: before introduction of the rapid molecular assay use (period 1) and after this (period 2).
Patients were included if they had upper respiratory samples tested for influenza by real-time reverse transcriptase polymerase chain reaction during two periods, using the ILI definition (coughing + temperature ≤ 38ºC) in period 1, and the definition of severe acute respiratory infection (ARS) (coughing + temperature ≤ 38ºC and dyspnoea) in period 2.