Maternal outcomes among pregnant women receiving live attenuated influenza vaccine.

Background: Although the live attenuated influenza vaccine (LAIV) prescribing information contains warnings/precautions against use during pregnancy, administration of LAIV to pregnant women does occur. Data regarding maternal outcomes after LAIV administration during pregnancy are limited.

Objectives: Maternal outcomes after LAIV vaccination during pregnancy were examined.

Methods: Data from a health insurance claims database that covers approximately 50 million individuals were analyzed for the six influenza seasons from 2003-2004 through 2008-2009. Emergency department (ED) visits and hospitalizations occurring within 42 days of vaccination were analyzed by primary diagnosis; outcomes were categorized as cardiopulmonary, obstetric, and other. Cohort characteristics were analyzed using descriptive statistics.

Results: Of 834,999 pregnancies identified, 138 (0·017%) were among women who received LAIV vaccinations. Of the 138 pregnant women, 13% were ≤19 years, 67% were 20-34 years, and 20% were ≥35 years of age. Eight events occurred within 42 days of vaccination: one ED visit for bronchitis, two hospitalizations for hyperemesis gravidarum and premature labor, and five ED visits/hospitalizations for common medical conditions. All outcomes identified after LAIV exposure occurred at rates similar to rates in unvaccinated pregnant women reported in the medical literature.

Conclusions: Administration of LAIV to pregnant women is rare; the rate has remained constant since 2004-2005. In this cohort, there was no evidence of significant maternal adverse outcomes after receipt of LAIV. These data may offer some reassurance to providers and pregnant women in the event of inadvertent LAIV administration, but do not support the routine use of LAIV in pregnant women.