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. 2014 Nov 12;312(18):1897-904.
doi: 10.1001/jama.2014.14825.

Evaluation of the Association of Maternal Pertussis Vaccination With Obstetric Events and Birth Outcomes

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Free PMC article

Evaluation of the Association of Maternal Pertussis Vaccination With Obstetric Events and Birth Outcomes

Elyse O Kharbanda et al. JAMA. .
Free PMC article

Abstract

Importance: 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.

Design and setting: Retrospective, observational cohort study using administrative health care databases from 2 California Vaccine Safety Datalink sites.

Participants and exposures: 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.

Main outcomes and measures: 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 and relevance: 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.

Conflict of interest statement

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Klein reported that she has received grant support from GlaxoSmithKline, Sanofi Pasteur, Pfizer, Merck & Co, Novartis, Nuron Biotech, Protein Science, and MedImmune. Dr Cheetham reported that he receives research support from Merck. Dr Naleway reported that she has received research support from GlaxoSmithKline. Dr DeStefano and Ms McCarthy reported that they are employees of the CDC and served as collaborators on this research. No other disclosures were reported.

Figures

Figure.
Figure.. Flowchart of Pregnancies Identified and Exclusions From 2 California Vaccine Safety Datalink Sites
Tdap indicates tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine.

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