Neonatal outcomes after antenatal influenza immunization during the 2009 H1N1 influenza pandemic

Impact on preterm birth, birth weight, and small for gestational age birth

Jennifer L. Richards, Craig Hansen, Christine Bredfeldt, Robert A. Bednarczyk, Mark C. Steinhoff, Dzifa Adjaye-Gbewonyo, Kevin Ault, Mia Gallagher, Walter Orenstein, Robert Davis, Saad B. Omer

Research output: Contribution to journalArticle

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Abstract

Background. Influenza infection during pregnancy is associated with adverse fetal outcomes such as preterm birth and small for gestational age (SGA). Maternal influenza immunization may prevent these adverse infant outcomes during periods of influenza circulation.Methods. We conducted a retrospective cohort study of live births within Kaiser Permanente (KP) Georgia and Mid-Atlantic States (n = 3327) during the period of 2009 influenza A (H1N1) virus circulation. Primary outcomes were third-trimester preterm birth (27-36 weeks), birth weight, low birth weight (LBW, <2500 g), and SGA.Results. There were 327 (9.8%) preterm, 236 (7.4%) LBW, and 267 (8.4%) SGA births. Among H1N1-vaccinated mothers (n = 1125), there were 86 (7.6%) preterm, 68 (6.4%) LBW, and 99 (9.3%) SGA births, and the mean birth weight was 3308.5 g (95% confidence interval [CI], 3276.6-3340.4). Among unvaccinated mothers (n = 1581), there were 191 (12.1%) preterm, 132 (8.8%) LBW, and 123 (8.2%) SGA births, and the mean birth weight was 3245.3 g (95% CI, 3216.5-3274.2). Infants of H1N1-vaccinated mothers had 37% lower odds of being born preterm than infants of unvaccinated mothers (adjusted odds ratio, 0.63 [95% CI,. 47-.84]). The mean birth weight difference between infants of H1N1-vaccinated mothers and infants of unvaccinated mothers was 45.1 g (95% CI, 1.8-88.3). There was no significant association between maternal H1N1 influenza immunization and LBW or SGA.Conclusions. Pregnant women who received H1N1 influenza vaccine were less likely to give birth preterm, and gave birth to heavier infants. The findings support US vaccine policy choices to prioritize pregnant women during the 2009 influenza A (H1N1) pandemic.

Original languageEnglish (US)
Pages (from-to)1216-1222
Number of pages7
JournalClinical Infectious Diseases
Volume56
Issue number9
DOIs
StatePublished - May 1 2013

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Premature Birth
Pandemics
Birth Weight
Human Influenza
Gestational Age
Immunization
Mothers
Parturition
Confidence Intervals
Pregnant Women
H1N1 Subtype Influenza A Virus
Influenza Vaccines
Influenza A virus
Third Pregnancy Trimester
Live Birth
Low Birth Weight Infant
Premature Infants
Cohort Studies
Vaccines
Retrospective Studies

All Science Journal Classification (ASJC) codes

  • Microbiology (medical)
  • Infectious Diseases

Cite this

Neonatal outcomes after antenatal influenza immunization during the 2009 H1N1 influenza pandemic : Impact on preterm birth, birth weight, and small for gestational age birth. / Richards, Jennifer L.; Hansen, Craig; Bredfeldt, Christine; Bednarczyk, Robert A.; Steinhoff, Mark C.; Adjaye-Gbewonyo, Dzifa; Ault, Kevin; Gallagher, Mia; Orenstein, Walter; Davis, Robert; Omer, Saad B.

In: Clinical Infectious Diseases, Vol. 56, No. 9, 01.05.2013, p. 1216-1222.

Research output: Contribution to journalArticle

Richards, JL, Hansen, C, Bredfeldt, C, Bednarczyk, RA, Steinhoff, MC, Adjaye-Gbewonyo, D, Ault, K, Gallagher, M, Orenstein, W, Davis, R & Omer, SB 2013, 'Neonatal outcomes after antenatal influenza immunization during the 2009 H1N1 influenza pandemic: Impact on preterm birth, birth weight, and small for gestational age birth', Clinical Infectious Diseases, vol. 56, no. 9, pp. 1216-1222. https://doi.org/10.1093/cid/cit045
Richards, Jennifer L. ; Hansen, Craig ; Bredfeldt, Christine ; Bednarczyk, Robert A. ; Steinhoff, Mark C. ; Adjaye-Gbewonyo, Dzifa ; Ault, Kevin ; Gallagher, Mia ; Orenstein, Walter ; Davis, Robert ; Omer, Saad B. / Neonatal outcomes after antenatal influenza immunization during the 2009 H1N1 influenza pandemic : Impact on preterm birth, birth weight, and small for gestational age birth. In: Clinical Infectious Diseases. 2013 ; Vol. 56, No. 9. pp. 1216-1222.
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abstract = "Background. Influenza infection during pregnancy is associated with adverse fetal outcomes such as preterm birth and small for gestational age (SGA). Maternal influenza immunization may prevent these adverse infant outcomes during periods of influenza circulation.Methods. We conducted a retrospective cohort study of live births within Kaiser Permanente (KP) Georgia and Mid-Atlantic States (n = 3327) during the period of 2009 influenza A (H1N1) virus circulation. Primary outcomes were third-trimester preterm birth (27-36 weeks), birth weight, low birth weight (LBW, <2500 g), and SGA.Results. There were 327 (9.8{\%}) preterm, 236 (7.4{\%}) LBW, and 267 (8.4{\%}) SGA births. Among H1N1-vaccinated mothers (n = 1125), there were 86 (7.6{\%}) preterm, 68 (6.4{\%}) LBW, and 99 (9.3{\%}) SGA births, and the mean birth weight was 3308.5 g (95{\%} confidence interval [CI], 3276.6-3340.4). Among unvaccinated mothers (n = 1581), there were 191 (12.1{\%}) preterm, 132 (8.8{\%}) LBW, and 123 (8.2{\%}) SGA births, and the mean birth weight was 3245.3 g (95{\%} CI, 3216.5-3274.2). Infants of H1N1-vaccinated mothers had 37{\%} lower odds of being born preterm than infants of unvaccinated mothers (adjusted odds ratio, 0.63 [95{\%} CI,. 47-.84]). The mean birth weight difference between infants of H1N1-vaccinated mothers and infants of unvaccinated mothers was 45.1 g (95{\%} CI, 1.8-88.3). There was no significant association between maternal H1N1 influenza immunization and LBW or SGA.Conclusions. Pregnant women who received H1N1 influenza vaccine were less likely to give birth preterm, and gave birth to heavier infants. The findings support US vaccine policy choices to prioritize pregnant women during the 2009 influenza A (H1N1) pandemic.",
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AU - Bednarczyk, Robert A.

AU - Steinhoff, Mark C.

AU - Adjaye-Gbewonyo, Dzifa

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N2 - Background. Influenza infection during pregnancy is associated with adverse fetal outcomes such as preterm birth and small for gestational age (SGA). Maternal influenza immunization may prevent these adverse infant outcomes during periods of influenza circulation.Methods. We conducted a retrospective cohort study of live births within Kaiser Permanente (KP) Georgia and Mid-Atlantic States (n = 3327) during the period of 2009 influenza A (H1N1) virus circulation. Primary outcomes were third-trimester preterm birth (27-36 weeks), birth weight, low birth weight (LBW, <2500 g), and SGA.Results. There were 327 (9.8%) preterm, 236 (7.4%) LBW, and 267 (8.4%) SGA births. Among H1N1-vaccinated mothers (n = 1125), there were 86 (7.6%) preterm, 68 (6.4%) LBW, and 99 (9.3%) SGA births, and the mean birth weight was 3308.5 g (95% confidence interval [CI], 3276.6-3340.4). Among unvaccinated mothers (n = 1581), there were 191 (12.1%) preterm, 132 (8.8%) LBW, and 123 (8.2%) SGA births, and the mean birth weight was 3245.3 g (95% CI, 3216.5-3274.2). Infants of H1N1-vaccinated mothers had 37% lower odds of being born preterm than infants of unvaccinated mothers (adjusted odds ratio, 0.63 [95% CI,. 47-.84]). The mean birth weight difference between infants of H1N1-vaccinated mothers and infants of unvaccinated mothers was 45.1 g (95% CI, 1.8-88.3). There was no significant association between maternal H1N1 influenza immunization and LBW or SGA.Conclusions. Pregnant women who received H1N1 influenza vaccine were less likely to give birth preterm, and gave birth to heavier infants. The findings support US vaccine policy choices to prioritize pregnant women during the 2009 influenza A (H1N1) pandemic.

AB - Background. Influenza infection during pregnancy is associated with adverse fetal outcomes such as preterm birth and small for gestational age (SGA). Maternal influenza immunization may prevent these adverse infant outcomes during periods of influenza circulation.Methods. We conducted a retrospective cohort study of live births within Kaiser Permanente (KP) Georgia and Mid-Atlantic States (n = 3327) during the period of 2009 influenza A (H1N1) virus circulation. Primary outcomes were third-trimester preterm birth (27-36 weeks), birth weight, low birth weight (LBW, <2500 g), and SGA.Results. There were 327 (9.8%) preterm, 236 (7.4%) LBW, and 267 (8.4%) SGA births. Among H1N1-vaccinated mothers (n = 1125), there were 86 (7.6%) preterm, 68 (6.4%) LBW, and 99 (9.3%) SGA births, and the mean birth weight was 3308.5 g (95% confidence interval [CI], 3276.6-3340.4). Among unvaccinated mothers (n = 1581), there were 191 (12.1%) preterm, 132 (8.8%) LBW, and 123 (8.2%) SGA births, and the mean birth weight was 3245.3 g (95% CI, 3216.5-3274.2). Infants of H1N1-vaccinated mothers had 37% lower odds of being born preterm than infants of unvaccinated mothers (adjusted odds ratio, 0.63 [95% CI,. 47-.84]). The mean birth weight difference between infants of H1N1-vaccinated mothers and infants of unvaccinated mothers was 45.1 g (95% CI, 1.8-88.3). There was no significant association between maternal H1N1 influenza immunization and LBW or SGA.Conclusions. Pregnant women who received H1N1 influenza vaccine were less likely to give birth preterm, and gave birth to heavier infants. The findings support US vaccine policy choices to prioritize pregnant women during the 2009 influenza A (H1N1) pandemic.

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