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Clinical Trial
. 2018 Mar 26;13(3):e0194392.
doi: 10.1371/journal.pone.0194392. eCollection 2018.

Severe influenza A(H1N1)pdm09 in pregnant women and neonatal outcomes, State of Sao Paulo, Brazil, 2009

Ana Freitas Ribeiro  1   2 , Alessandra Cristina Guedes Pellini  1 , Beatriz Yuko Kitagawa  1 , Daniel Marques  1 , Geraldine Madalosso  1 , Joao Fred  1 , Ricardo Kerti Mangabeira Albernaz  1 , Telma Regina Marques Pinto Carvalhanas  1 , Dirce Maria Trevisan Zanetta  2
Affiliations
Clinical Trial

Severe influenza A(H1N1)pdm09 in pregnant women and neonatal outcomes, State of Sao Paulo, Brazil, 2009

Ana Freitas Ribeiro et al. PLoS One. .

Abstract

To investigate the factors associated with death and describe the gestational outcomes in pregnant women with influenza A(H1N1)pdm09, we conducted a case-control study (deaths and recovered) in hospitalized pregnant women with laboratory-confirmed influenza A(H1N1)pdm09 with severe acute respiratory illness (SARI) in the state of São Paulo from June 9 to December 1, 2009. All cases were evaluated, and four controls that were matched by the epidemiological week of hospitalization of the case were randomly selected for each case. Cases and controls were selected from the National Disease Notification System-SINAN Influenza-web. The hospital records from 126 hospitals were evaluated, and home interviews were conducted using standardized forms. A total of 48 cases and 185 controls were investigated. Having had a previous health visit to a healthcare provider for an influenza episode before hospital admission was a risk factor for death (adjusted OR (ORadj) of 7.93, 95% CI 2.19-28.69). Although not significant in the multiple analysis (ORadj of 2.13, 95% CI 0.91-5.00), the 3rd trimester deserves attention, with an OR = 2.22, 95% CI 1.13-4.37 in the univariate analysis. Antiviral treatment was a protective factor when administered within 48 hours of symptom onset (ORadj = 0.16, 95% CI 0.05-0.50) and from 48 to 72 hours (ORadj = 0.09, 95% CI 0.01-0.87). There was a higher proportion of fetal deaths and preterm births among cases (p = 0.001) and live births with low weight (p = 0.019), compared to control subjects who gave birth during hospitalization. After discharge, control subjects had a favorable neonatal outcome. Early antiviral treatment during the presence of a flu-like illness is an important factor in reducing mortality from influenza in pregnant women and unfavorable neonatal outcomes. It is important to monitor pregnant women, particularly in the 3rd trimester of gestation, with influenza illness for diagnosis and early treatment.

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Conflict of interest statement

Competing Interests: AFR was speaker in two masterclass events about Influenza, organized by Sanofi Pasteur. The presentations occurred in 2014 and 2015, after the conclusion of her PhD at the University of São Paulo, São Paulo, Brazil, about the risk factors for death due to influenza A (H1N1)pdm09. There was no interference in the development of the study (2010 and 2011) and analysis of the data presented in this manuscript. The remaining authors report no conflict of interest. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1
Fig 1. Flow chart for the selection of cases and controls among pregnant women reported in the National Disease Notification System—SINAN—São Paulo State, 2009.
See this image and copyright information in PMC

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