Document Detail

Risks and safety of pandemic h1n1 influenza vaccine in pregnancy: Birth defects, spontaneous abortion, preterm delivery, and small for gestational age infants.
MedLine Citation:
PMID:  24016809     Owner:  NLM     Status:  Publisher    
INTRODUCTION: There is a need for additional information on the fetal risks and relative safety of the pandemic H1N1 monovalent or trivalent influenza (pH1N1)-containing vaccines in women exposed during pregnancy.
METHODS: To assess risks and relative safety of the pH1N1-containing vaccines, we conducted a prospective cohort study of pH1N1-vaccine-exposed and unexposed comparison women residing in the U.S. or Canada who were recruited during pregnancy and followed to outcome between October 2009 and August 2012. For exposure to the pH1N1 vaccine, adjusted relative risks (RRs) and 95% confidence intervals (CIs) were estimated for major birth defects and infants small for gestational age. Adjusted hazard ratios (HRs) and 95% CIs were estimated for spontaneous abortion and preterm delivery for time-varying exposure.
RESULTS: There were 1032 subjects available for analysis; 841 women were exposed to a pH1N1-containing vaccine in pregnancy, and 191 women were unexposed to any influenza vaccine in pregnancy. Nine of 328 (2.7%) first-trimester-exposed pregnancies resulted in an infant with a major birth defect compared to 6/188 (3.2%) in the unexposed (adjusted RR 0.79, 95% CI 0.26-2.42). The HR for spontaneous abortion was not elevated (adjusted HR 0.92, 95% CI 0.31-2.72). Adjusted HRs for preterm delivery were elevated for exposure anytime in pregnancy (3.28, 95% CI 1.25-8.63), specifically with exposure in the 1st or 2nd trimester. However, the mean decrease in gestational age in the exposed pregnancies was approximately three days. Adjusted RRs for small for gestational age infants on weight and length approximated 1.0.
CONCLUSIONS: For the 2009-12 influenza seasons combined, we found no meaningful evidence of increased RR or HR for major birth defects, spontaneous abortion, or small for gestational age infants. There was some evidence of an increased HR for preterm delivery following pH1N1-influenza vaccine exposure; however the decrease in gestational age on average was approximately three days.
Christina D Chambers; Diana Johnson; Ronghui Xu; Yunjun Luo; Carol Louik; Allen A Mitchell; Michael Schatz; Kenneth L Jones;
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-9-6
Journal Detail:
Title:  Vaccine     Volume:  -     ISSN:  1873-2518     ISO Abbreviation:  Vaccine     Publication Date:  2013 Sep 
Date Detail:
Created Date:  2013-9-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8406899     Medline TA:  Vaccine     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2013. Published by Elsevier Ltd.
Department of Pediatrics, University of California San Diego, La Jolla, CA, United States; Rady Children's Hospital, San Diego, CA, United States; Department of Family and Preventive Medicine, University of California San Diego, La Jolla, CA, United States; Clinical Translational Research Institute, University of California San Diego, La Jolla, CA, United States; Vaccines and Medications in Pregnancy Surveillance System, United States. Electronic address:
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