Influenza Pandemics—Pregnancy, Pathogenesis, and Perinatal Outcomes

Steinhoff, Mark C.; MacDonald, Noni E.

doi:10.1001/jama.2012.7911

Cited by 13 publications

(8 citation statements)

References 17 publications

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“…congenital cytomegalovirus, rubella, varicella), potential pathogenic effects of influenza viruses on the fetus are not. As the influenza virus is rarely transmitted across the placenta, influenza virus infection is more likely to be associated with adverse birth outcomes through other mechanisms such as maternal fever and inflammation . Immunological responses, such as elevated pro‐inflammatory cytokine levels, can also influence placental function and are recognised as an important pathway to preterm birth .…”

Section: Discussionmentioning

confidence: 99%

Maternal influenza and birth outcomes: systematic review of comparative studies

Fell

Savitz

Kramer

et al. 2016

BJOG

137

111

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BackgroundAlthough pregnant women are considered at high risk for severe influenza disease, comparative studies of maternal influenza and birth outcomes have not been comprehensively summarised.ObjectiveTo review comparative studies evaluating maternal influenza disease and birth outcomes.Search strategyWe searched bibliographic databases from inception to December 2014.Selection criteriaStudies of preterm birth, small‐for‐gestational‐age (SGA) birth or fetal death, comparing women with and without clinical influenza illness or laboratory‐confirmed influenza infection during pregnancy.Data collection and analysisTwo reviewers independently abstracted data and assessed study quality.Main resultsHeterogeneity across 16 studies reporting preterm birth precluded meta‐analysis. In a subgroup of the highest‐quality studies, two reported significantly increased preterm birth (risk ratios (RR) from 2.4 to 4.0) following severe 2009 pandemic H1N1 (pH1N1) influenza illness, whereas those assessing mild‐to‐moderate pH1N1 or seasonal influenza found no association. Five studies of SGA birth showed no discernible patterns with respect to influenza disease severity (pooled odds ratio 1.24; 95% CI 0.96–1.59). Two fetal death studies were of sufficient quality and size to permit meaningful interpretation. Both reported an increased risk of fetal death following maternal pH1N1 disease (RR 1.9 for mild‐to‐moderate disease and 4.2 for severe disease).ConclusionsComparative studies of preterm birth, SGA birth and fetal death following maternal influenza disease are limited in number and quality. An association between severe pH1N1 disease and preterm birth and fetal death was reported by several studies; however, these limited data do not permit firm conclusions on the magnitude of any association.Tweetable abstractComparative studies are limited in quality but suggest severe pandemic H1N1 influenza increases preterm birth.

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Section: Discussionmentioning

confidence: 99%

Maternal influenza and birth outcomes: systematic review of comparative studies

Fell

Savitz

Kramer

et al. 2016

BJOG

137

111

View full text Add to dashboard Cite

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“…Inoculation against influenza has been a public health strategy for many years, and is considered to be the most effective means of preventing influenza and mitigating severe illness . Theoretically, prevention of maternal influenza through vaccination could benefit the fetus by averting symptoms such as hyperthermia, or consequences of illness influencing placental function . However, this theoretical benefit is only plausible insofar as there is an independent risk of adverse pregnancy outcomes attributable to maternal influenza.…”

Section: Discussionmentioning

confidence: 99%

Fetal death and preterm birth associated with maternal influenza vaccination: systematic review

Fell

Platt

Lanes

et al. 2014

BJOG

109

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Background Before 2012, few studies had addressed pregnancy outcomes following maternal influenza vaccination; however, the number of publications on this topic has increased recently. Objectives To review comparative studies evaluating fetal death or preterm birth associated with influenza vaccination during pregnancy. Search strategy We searched bibliographic databases from inception to April 2014. Selection criteria Experimental or observational studies assessing the relationship between influenza vaccination during pregnancy and fetal death or preterm birth. Data collection and analysis Two reviewers independently abstracted data from studies meeting the inclusion criteria. Main results We included one randomised clinical trial and 26 observational studies. Meta‐analyses were not considered appropriate because of high clinical and statistical heterogeneity. Three studies of fetal death at any gestational age reported adjusted effect estimates in the range 0.56–0.79, and four of five studies of fetal death at <20 weeks reported adjusted estimates between 0.89 and 1.23, all with confidence intervals including 1.0. Adjusted effect estimates for four of five studies of fetal death at ≥20 weeks ranged from 0.44 to 0.77 (two with confidence intervals not crossing 1.0), whereas a fifth reported a non‐significant effect in the opposite direction. Among 19 studies of preterm birth, there was no strong evidence suggesting any increased risk, and meta‐regression did not explain the moderate between‐study heterogeneity (I2 = 57%). Authors' conclusions Most studies reported no association between fetal death or preterm birth and influenza vaccination during pregnancy. Although several reported risk reductions, results may be biased by methodological shortcomings of observational studies of influenza vaccine effectiveness.

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“…Clinical efficacy of the IIV and the size of its effect remain subjects of debate due to the scarcity of randomized trials; the interpretation of results of other trials can be complicated by the fact that observational studies are prone to biases. Most data from non‐randomized trials suggest that vaccination during pregnancy confers clinical benefits in both the pregnant woman and her newborn . For example, respiratory illness with fever has been shown to be reduced in pregnant women, while in infants, findings include a reduction in laboratory‐confirmed influenza (LCI) and number of small‐for‐gestational‐age babies, along with higher birth weights .…”

Section: Clinical Benefit Of the Influenza Vaccination During Pregnancymentioning

confidence: 99%

“…Most data from non-randomized trials suggest that vaccination during pregnancy confers clinical benefits in both the pregnant woman and her newborn. 6,30,[46][47][48][49] For example, respiratory illness with fever has been shown to be reduced in pregnant women, while in infants, findings include a reduction in laboratory-confirmed influenza (LCI) and number of small-for-gestational-age babies, along with higher birth weights. 6,47 A case-controlled study found that 42% of pregnant women with confirmed influenza had been vaccinated during the study season compared to 58% and 63% among influenza-negative controls and matched acute respiratory infection-negative controls, respectively, for a vaccine efficacy of 44-53%.…”

Section: Clinical Benefit Of the Influenza Vaccination During Pregnancymentioning

confidence: 99%

The Global Influenza Initiative recommendations for the vaccination of pregnant women against seasonal influenza

Macías

Precioso

Falsey

2015

Influenza Resp Viruses

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There is a heavy disease burden due to seasonal influenza in pregnant women, their fetuses, and their newborns. The main aim of this study was to review and analyze current evidence on safety, immunogenicity, and clinical benefits of the inactivated influenza vaccine (IIV) in pregnant women. Current evidence shows that in pregnant women, the seasonal and pandemic IIVs are safe and well tolerated. After vaccination, pregnant women have protective concentrations of anti-influenza antibodies, conferring immunogenicity in newborns. The best evidence, to date, suggests that influenza vaccination confers clinical benefits in both pregnant women and their newborns. Vaccination with either the seasonal or pandemic vaccine has been shown to be cost-effective in pregnancy. There are scarce data from randomized clinical trials; fortunately, new phase 3 clinical trials are under way. In the Northern and Southern Hemispheres, data suggest that the greatest clinical benefit for infants occurs if the IIV is administered within the first weeks of availability of the vaccine, at the beginning of the influenza season, regardless of the pregnancy trimester. The optimal timing to vaccinate pregnant women who live in tropical regions is unclear. Based on evaluation of the evidence, the Global Influenza Initiative (GII) recommends that to prevent seasonal influenza morbidity and mortality in infants and their mothers, all pregnant women, regardless of trimester, should be vaccinated with the IIV. For countries where vaccination against influenza is starting or expanding, the GII recommends that pregnant women have the highest priority.

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Influenza Pandemics—Pregnancy, Pathogenesis, and Perinatal Outcomes

Cited by 13 publications

References 17 publications

Maternal influenza and birth outcomes: systematic review of comparative studies

Maternal influenza and birth outcomes: systematic review of comparative studies

Fetal death and preterm birth associated with maternal influenza vaccination: systematic review

The Global Influenza Initiative recommendations for the vaccination of pregnant women against seasonal influenza

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