Evaluation of the association of maternal pertussis vaccination with obstetric events and birth outcomes.
OBJECTIVE
In 2010, due to a pertussis outbreak and neonatal deaths, the California Department of Health recommended that the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) be administered during pregnancy. Tdap is now recommended by the Advisory Committee on Immunization Practices for all pregnant women, preferably between 27 and 36 weeks' gestation. Limited data exist on Tdap safety during pregnancy.


OBJECTIVE
To evaluate whether maternal Tdap vaccination during pregnancy is associated with increased risks of adverse obstetric events or adverse birth outcomes.


METHODS
Retrospective, observational cohort study using administrative health care databases from 2 California Vaccine Safety Datalink sites.


METHODS
Of 123,494 women with singleton pregnancies ending in a live birth between January 1, 2010, and November 15, 2012, 26,229 (21%) received Tdap during pregnancy and 97,265 did not.


METHODS
Risks of small-for-gestational-age (SGA) births (<10th percentile), chorioamnionitis, preterm birth (<37 weeks' gestation), and hypertensive disorders of pregnancy were evaluated. Relative risk (RR) estimates were adjusted for site, receipt of another vaccine during pregnancy, and propensity to receive Tdap during pregnancy. Cox regression was used for preterm delivery, and Poisson regression for other outcomes.


RESULTS
Vaccination was not associated with increased risks of adverse birth outcomes: crude estimates for preterm delivery were 6.3% of vaccinated and 7.8% of unvaccinated women (adjusted RR, 1.03; 95% CI, 0.97-1.09); 8.4% of vaccinated and 8.3% of unvaccinated had an SGA birth (adjusted RR, 1.00; 95% CI, 0.96-1.06). Receipt of Tdap before 20 weeks was not associated with hypertensive disorder of pregnancy (adjusted RR, 1.09; 95% CI, 0.99-1.20); chorioamnionitis was diagnosed in 6.1% of vaccinated and 5.5% of unvaccinated women (adjusted RR, 1.19; 95% CI, 1.13-1.26).


CONCLUSIONS
In this cohort of women with singleton pregnancies that ended in live birth, receipt of Tdap during pregnancy was not associated with increased risk of hypertensive disorders of pregnancy or preterm or SGA birth, although a small but statistically significant increased risk of chorioamnionitis diagnosis was observed.
HealthPartners Institute for Education and Research, Minneapolis, Minnesota.
Elyse O
EO
Kharbanda
HealthPartners Institute for Education and Research, Minneapolis, Minnesota.
Gabriela
G
Vazquez-Benitez
Obstetrics and Gynecology, Yale University, New Haven, Connecticut.
Heather S
HS
Lipkind
Kaiser Permanente of Northern California, Oakland.
Nicola P
NP
Klein
Kaiser Permanente Southern California, Pasadena.
T Craig
TC
Cheetham
Kaiser Permanente Northwest, Portland, Oregon.
Allison
A
Naleway
Kaiser Permanente Georgia, Atlanta.
Saad B
SB
Omer
Institute for Health Research, Kaiser Permanente Colorado, Denver8Department of Ambulatory Care Services, Denver Health, Denver, Colorado.
Simon J
SJ
Hambidge
Harvard Pilgrim Health Care Institute, Boston, Massachusetts10Harvard Medical School, Boston, Massachusetts.
Grace M
GM
Lee
Group Health Cooperative, Seattle, Washington.
Michael L
ML
Jackson
Centers for Disease Control and Prevention, Atlanta, Georgia.
Natalie L
NL
McCarthy
Centers for Disease Control and Prevention, Atlanta, Georgia.
Frank
F
DeStefano
HealthPartners Institute for Education and Research, Minneapolis, Minnesota.
James D
JD
Nordin
D000293:Adolescent; D000328:Adult; D002140:California / Q000453:epidemiology; D002821:Chorioamnionitis / Q000453:epidemiology*; D015331:Cohort Studies; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology*; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012189:Retrospective Studies; D012306:Risk; D014611:Vaccination / Q000009:adverse effects; D014917:Whooping Cough / Q000453:epidemiology / Q000517:prevention & control; D055815:Young Adult
D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines