Effect of influenza vaccination in the first trimester of pregnancy.
OBJECTIVE
To estimate the effect of first-trimester influenza vaccination on fetal and neonatal outcomes.


METHODS
This was a retrospective cohort study examining delivery and neonatal outcomes after antepartum exposure to the seasonal trivalent inactive influenza vaccine. Data were collected and entered into an established computerized database. Outcomes by trimester of vaccination were then compared with women who did not receive the vaccine.


RESULTS
During the 5-year study period, 10,225 women received the seasonal influenza vaccine antepartum; 8,690 of these delivered at our institution, 439 in the first trimester and 8,251 in the second and third trimesters. Women vaccinated antepartum were significantly older with higher parity than women who declined vaccination. Neonates born to mothers receiving the vaccine in any trimester did not have an increase in major malformations regardless of trimester of vaccination (2% regardless of vaccination group, P=.9). Stillbirth (0.3% compared with 0.6%, P=.006), neonatal death (0.2% compared with 0.4%, P=.01), and premature delivery (5% compared with 6%, P=.004) were significantly decreased in the vaccinated group.


CONCLUSIONS
Influenza vaccination in the first trimester was not associated with an increase in major malformation rates and was associated with a decrease in the overall stillbirth rate. This information will aid in counseling women regarding the safety of influenza vaccination in the first trimester.
University of Texas Southwestern Medical Center and Parkland Health & Hospital System, Dallas, Texas, USA. jeanne.sheffield@utsouthwestern.edu
Jeanne S
JS
Sheffield
Laura G
LG
Greer
Vanessa L
VL
Rogers
Scott W
SW
Roberts
Heather
H
Lytle
Donald D
DD
McIntire
George D
GD
Wendel
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000209:etiology; D005260:Female; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D007251:Influenza, Human / Q000517:prevention & control*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control*; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D047928:Premature Birth / Q000209:etiology / Q000517:prevention & control; D011295:Prenatal Care; D012189:Retrospective Studies; D050497:Stillbirth; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects; D055815:Young Adult
D007252:Influenza Vaccines; D015164:Vaccines, Inactivated