Risk of pregnancy complications and adverse birth outcomes after maternal A(H1N1)pdm09 influenza: a Norwegian population-based cohort study (original) (raw)
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Journal of Infectious Diseases, 2012
Background. Pregnant women were at increased risk for serious outcomes of 2009 pandemic influenza A virus subtype H1N1 (influenza A[H1N1]pdm09) infection, but little is known about the overall impact of the pandemic on neonatal and maternal outcomes. Methods. We identified live births that occurred from 1 July 2008 through 31 May 2010 in 5 Kaiser Permanente regions. Pregnant women were considered to have influenza if they had a positive result of a laboratory test for influenza virus or if they received a diagnosis of influenza during a period in which seasonal influenza virus or A(H1N1)pdm09 was the predominant circulating virus. Results. There were 111 158 births from 109 015 pregnancies involving 107 889 mothers; 368 pregnant women (0.3%) received a diagnosis of influenza due to seasonal virus, and 959 (0.9%) received a diagnosis of influenza due to A(H1N1)pdm09; 107 688 did not receive an influenza diagnosis. Pregnant women with influenza due to A(H1N1)pdm09 were more likely than women with seasonal influenza infection to be hospitalized within 30 days of the diagnosis (27% vs 12%; odds ratio [OR], 2.84 [95% confidence interval {CI}, 2.01-4.02]). Pregnant women with A(H1N1)pdm09 who started antiviral treatment ≥2 days after the diagnosis were significantly more likely to be hospitalized than those who started antiviral treatment <2 days after diagnosis (OR, 3.43 [95% CI, 1.55-7.56]). Mothers with seasonal influenza virus infection had an increased risk for having a small-forgestational-age infant (OR, 1.59 [95% CI, 1.15-2.20]). Conclusions. In this large, geographically diverse population, A(H1N1)pdm09 infection increased the risk for hospitalization during pregnancy. Late initiation of antiviral treatment was also associated with an increased risk for hospitalization.
EClinicalMedicine, 2020
Background: Our study aimed to assess the safety and protective effect of maternal influenza vaccination on pregnancy and birth outcomes. Methods: The study population comprised 1253 healthy nulliparous pregnant women in South Australia between 2015 and 2018. Participants were followed prospectively, with vaccination status (confirmed by medical records), pregnancy, and birth outcome data collected by midwives. Adjusted relative risks (aRRs) and adjusted hazard ratios (aHRs) were estimated accounting for time-varying vaccine exposure and temporal nature of each outcome. Findings: Maternal influenza vaccination (48%, 603 of 1253) reduced the risk for pre-delivery hospitalisation with influenza like illness (aHR 061; 95% CI 039, 097). Maternal influenza vaccination was not associated with spontaneous abortion (aHR 042, 95% CI 012, 145), chorioamnionitis (aRR 078, 95% CI, 032, 188), gestational hypertension (aHR 078, 95% CI 047, 129), pre-eclampsia (aHR 0.84, 95% CI 054, 127), gestational diabetes (aHR 116, 95% CI 082, 166) nor preterm birth (aHR 094, 95% CI 059, 149). No associations between antenatal influenza vaccination and congenital anomalies, admission to the neonatal care unit, low Apgar scores, and mechanical ventilation were observed. Results were not materially changed after adjustment for pertussis vaccination. We observed a protective effect of maternal influenza vaccination on low birth weight (aHR 046, 95% CI 023, 094) and a marginal protective effect on small for gestational age births (aHR 065, 95% CI 040, 104) during periods of high influenza activity. Interpretation: These results support the safety of maternal influenza vaccination and suggest a protective effect in reducing the rates of low birthweight and small for gestational age births. Funding: There was no funding for this study.
Background/Aims: Impaired pregnancy outcomes, such as low birth weight are associated with increased disease risk in later life, however little is known about the impact of common infectious diseases during pregnancy on birth weight. The study had two aims: a) to investigate risk factors of influenza virus infection during pregnancy, and b) to analyze the impact of influenza virus infection on pregnancy outcome, especially birth weight. Methods: Prospective and retrospective observational studies found in PubMed, MEDLINE, Embase, Google Scholar, and WangFang database were included in this meta analysis. Data of included studies was extracted and analyzed by the RevMan software. Results: Pregnant women with anemia (P=0.004, RR=1.46, 95% CI: 1.13-1.88), obesity (P<0.00001, RR=1.35, 95% CI: 1.25-1.46) and asthma (P<0.00001, RR=1.99, 95% CI: 1.67-2.37) had higher rates of influenza virus infection. Regarding birth outcomes, influenza A virus infection did not affect the likelihood for cesarean section. Mothers with influenza had a higher rate of stillbirth (P=0.04, RR=2.36, 95% CI: 1.05-5.31), and their offspring had low 5-minute APGR Scores (P=0.009, RR=1.39, 95% CI: 1.08-1.79). Furthermore, the rate for birth weight < 2500g (P=0.04, RR=1.71, 95% CI: 1.03-2.84) was increased. Conclusion: Results of this study showed that anemia, asthma and obesity during pregnancy are risk factors influenza A virus infection during pregnancy. Moreover, gestational influenza A infection impairs pregnancy outcomes and increases the risk for low birth weight, a known risk factor for later life disease susceptibility.
Postpandemic Influenza A/H1N1pdm09 is still Causing Severe Perinatal Complications
Mediterranean journal of hematology and infectious diseases, 2015
Although influenza A/H1N1pdm09 is not causing a pandemic anymore, we recently observed two critically ill pregnant women infected by this virus. We present these cases to illustrate the possible severe complications of an - at that moment - seasonal influenza in pregnancy. We discuss the epidemiological differences between the pandemic and post pandemic phase and try to explain the high virulence of influenza A/H1N1pdm09 -infections in pregnancy by discussing insights in immunology during pregnancy. We conclude that although influenza A/H1N1pdm09 is in the post pandemic phase, infection by this influenza virus still needs to be considered in pregnant women with progressive respiratory dysfunction.
Vaccine, 2014
Pregnant women and their infants are vulnerable to severe disease and secondary complications from influenza infection. For this reason, annual influenza vaccination is recommended for all pregnant women in the United States. Women frequently cite concerns about vaccine safety as a barrier to vaccination. This review describes the safety of inactivated influenza vaccination during pregnancy with a focus on maternal obstetric events, including hypertensive disorders, gestational diabetes, and chorioamnionitis. Included in the review are new findings from two studies which examined the safety of seasonal inactivated influenza vaccination during pregnancy. The first study enrolled 641 pregnant women during the 2010-2011 season and prospectively followed them until delivery or pregnancy termination. The second study enrolled 1616 pregnant women during the 2010-2011 influenza season, and followed the women and their infants for six months after delivery. No associations between inactivated influenza vaccination and gestational diabetes, gestational hypertension, preeclampsia/eclampsia, or chorioamnionitis were observed in either cohort. When considered as a whole, these studies should further reassure women and clinicians that influenza vaccination during pregnancy is safe for mothers.
Influenza infections in the 2014–2015 season and pregnancy outcomes
Journal of Infection in Developing Countries, 2017
Introduction: The most recent influenza season saw a prominent infectious burden over a period of six months in the Turkish capital, reminding observers of the pandemic in 2009 year. The aim of the present study was to investigate the consequences of seasonal outbreaks in pregnant women during the 2014-2015 influenza season. Methodology: Forty-seven pregnant female patients with symptoms of influenza-like illness who were admitted to tertiary perinatal care center in Ankara, Tukrey, between October 2014 and May 2015 were included in this case-control study. The subtype determination of influenza was performed with real-time reverse transcriptase-polymerase chain reaction (RT-PCR) testing. Clinical observations and pregnancy outcomes were compared with respect to subtypes. Results: Classifications were available for 35 patients, of whom 12 were determined to have influenza A infection, while 10 had influenza B infection. The remaining 13 patients were influenza-negative. Eight of the 22 (36.4%) influenza-positive patients delivered their babies in the preterm period (< 37 weeks). The corresponding rate was 8.3% (1/12) in the influenza-negative group. This difference was not statistically significant (p = 0.077). Conclusions: Preterm deliveries in pregnant women did not differ significantly among influenza-postive and influenza-negative pregnant women in non-vaccinated study population. Further studies with larger sample sizes may provide more supporting results.
American Journal of Obstetrics and Gynecology, 2011
T he emergence of 2009 pandemic influenza A (H1N1) virus (2009 H1N1) resulted in the first influenza pandemic in over 40 years. The Centers for Disease Control and Prevention (CDC) estimated that about 61 million people were infected, 274,000 were hospitalized, and about 12,740 died due to 2009 H1N1 in the United States. 1 About 90% of all hospitalizations and 87% of all deaths during the 2009 H1N1 pandemic were among people Ͻ65 years in contrast with experience from seasonal influenza when about 40% of all hospitalizations and 10% of deaths were found in this age group. 1 It is well recognized that pregnancy represents a risk factor for influenza complications and death during both pandemic and seasonal influenza. 2-6 Thus, with illness being widespread among the younger segments of the population We sought to describe characteristics of hospitalized reproductive-aged (15-44 years) women with seasonal (2005/2006 through 2008/2009) and 2009 pandemic influenza A (H1N1) virus infection. We used population-based data from the Emerging Infections Program in 10 US states, and compared characteristics of pregnant (n ϭ 150) and nonpregnant (n ϭ 489) seasonal, and pregnant (n ϭ 489) and nonpregnant (n ϭ 1088) pandemic influenza cases using 2 and Fisher's exact tests. Pregnant women represented 23.5% and 31.0% of all reproductive-aged women hospitalized for seasonal and pandemic influenza, respectively. Significantly more nonpregnant than pregnant women with seasonal (71.2% vs 36.0%) and pandemic (69.7% vs 31.9%) influenza had an underlying medical condition other than pregnancy. Antiviral treatment was significantly more common with pandemic than seasonal influenza for both pregnant (86.5% vs 24.0%) and nonpregnant (82.0% vs 55.2%) women. Pregnant women comprised a significant proportion of influenza-hospitalized reproductive-aged women, underscoring the importance of influenza vaccination during pregnancy.
American Journal of Obstetrics and Gynecology, 2011
The purpose of this study was to describe the neonatal characteristics and outcomes of infants who were born during the 2009 H1N1 influenza pandemic. A prospective cohort of pregnant women with influenza-like illness (ILI) was enrolled between the months of June 2009 and March 2010. Neonatal characteristics, complications, and outcomes were recorded. Forty-five women were included in the study. Birth outcomes were available in 41 cases; 16 women had 2009 H1N1 infection, and the remaining 25 women who tested negative were included in the ILI group. Live births were similar in both groups. Average gestational age at delivery was Ͼ39 weeks; Apgar scores and cord gas pH values were similar. Birthweights in the 2009 H1N1 group were on average 285 g lower (3186 vs 3471 g; P ϭ .04). Three infants were admitted to the neonatal intensive care unit. In this cohort, 2009 H1N1 infection during pregnancy was associated with a lower birthweight when compared with ILI in pregnancy.
Influenza A H1N1 2009 (Swine Flu) and Pregnancy
The Journal of Obstetrics and Gynecology of India, 2011
The Influenza A H1N1 pandemic (A H1N1) occurred between June 2009 and August 2010. Although the pandemic is now over, the virus has emerged as the predominant strain in the current seasonal influenza phase in the northern hemisphere. The A H1N1 influenza is a novel strain of the influenza A virus and is widely known as swine flu. The virus contains a mixture of genetic material from human, pig and bird flu virus. It is a new variety of flu which people have not had much immunity to. Much has been learnt from the Pandemic of 2009/2010 but the messages about vaccination and treatment seem to be taken slowly by the clinical profession. Most people affected by the virus, including pregnant women, suffer a mild viral illness, and make a full recovery. The median duration of illness is around seven days. This influenza typically affects the younger age group i.e. from the ages of 5-65 years. Current experience shows that the age group experiencing increased morbidity and mortality rates are in those under 65 years of age. Pregnant women, because of their altered immunity and physiological adaptations, are at higher risk of developing pulmonary complications, especially in the second and third trimesters. In the United Kingdom, twelve maternal deaths were reported to be associated with the H1N1 virus during the pandemic and clear avoidable factors were identified (Modder, Review of Maternal Deaths in the UK related to A H1N1 2009 influenza (CMACE). www.cmace.org.uk, 2010). The pregnancy outcomes were also poor for women who were affected by the virus with a fivefold increase in the perinatal mortality rate and threefold increase in the preterm delivery rate (Yates et al. Health Technol Assess 14(34):109-182, 2010). There continues to be a low uptake of the flu vaccine and commencement of antiviral treatment for pregnant women.