| Abstract |
Introduction: Pregnancy is a period of increased morbidity and mortality, especially
during seasonal influenza. Studies suggest that influenza infections during pregnancy
may increase the risk of developmental and neurological disorders in the foetus and
the infant.
Objectives: The main objective of the study was to measure the incidence of
influenza infection among pregnant women in Heraklion prefecture, and to identify
possible risk factors (socio-economic and co-morbidities) associated with the
disease. Secondary objectives included (1) the estimation of influenza vaccination
coverage among pregnant women and (2) assessing the feasibility of sampling
(using throat swabs) for the identification of the influenza virus during populationbased
studies (pilot study).
Methods: The study was conducted from 21/02/2007 to 20/02/2008 as part of a large
prospective mother-child cohort study (“Rhea”). The study population included all
pregnant women who lived in Heraklion prefecture. To collect data, face to face
interviews were conducted using three standardized questionnaires, one for each
trimester of pregnancy. Probable case was defined as a pregnant woman living in the
study area, who reported fever (temperature>37.5oC) and at least two of the following
clinical symptoms: cough, sore throat, sneeze, myalgia/arthralgia, headache,
weakness, shiver. Additionally, throat swabs were collected from the 1/3 of the
probable cases and were analyzed using Real Time PCR in Pasteur Institute, in
order to detect and identify the virus (pilot study).
Results: Among the 1416 participants, 1359 (96%) completed the 1st trimester
questionnaire, 739 (52%) the 2nd trimester and 635 (26%) the 3rd. The risk of selfreported
influenza was 23% during the 1st trimester and 22% during the second one,
whereas using the more specific case-definition, the risk was found 5%, 2,3% and
1,3% for each trimester of pregnancy, respectively. Just 1% of the subjects had been
vaccinated against influenza virus during the 1st trimester of pregnancy and 2%
during the second. The risk of probable influenza was 3 times higher (adjusted
RR=2,8 95%CI 0,64-12,3) in those living in overcrowded households (>5 household
members) and 9 times higher (adjusted RR=8,9 95%CI 2,16-36,2) in subjects that
reported contact with another influenza case in the household. Women who
continued working during the 2nd trimester of pregnancy were twice more likely
(adjusted RR=2,4 95%CI 1,09-5,12) to become ill with influenza, compared with
those who were on pregnancy leave. The risk of influenza was 5 times higher
(adjusted RR=5 95%CI 1,53-16,5) in women with asthma attacks during the 2nd
trimester of pregnancy. Fifty percent of the throat swabs tested were found positive
for influenza virus.
Conclusion: Contact with a case in the household, overcrowding, working during the
2nd trimester of pregnancy and previous asthma attacks were found to be strongly
associated with the risk of influenza infection during pregnancy. The pilot study
suggests that despite being very useful, the use of throat swabs for the identification
of the influenza virus appears to be a logistically complicated procedure during large
scale population-based studies.
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"Ο ιός της γρίπης κατά τη διάρκεια της εγκυμοσύνης". Μέρος της προοπτικής μελέτης Μητέρας-Παιδιού στην Κρήτη, ΡΕΑ
