Evaluation of the Association of Maternal Pertussis Vaccination With Obstetric Events and Birth Outcomes. Issue 3 (March 2015)

• Record Type: Journal Article
• Authors: Kharbanda, Elyse O.; Vazquez-Benitez, Gabriela; Lipkind, Heather S.; Klein, Nicola P.; Cheetham, T. Craig; Naleway, Allison; Omer, Saad B.; Hambidge, Simon J.; Lee, Grace M.; Jackson, Michael L.; McCarthy, Natalie L.; DeStefano, Frank; Nordin, James D.
• Is Part Of: Obstetrical & gynecological survey. Volume 70:Issue 3(2015)
• Publication Date: 2015-03
• Subjects: Obstetrics -- Periodicals; Gynecology -- Periodicals; Generative organs, Female -- Surgery -- Periodicals; 618
• DOI: 10.1097/OGX.0000000000000175
• Languages: English
• ISSNs: 0029-7828

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>ABSTRACT</title> <p> <italic>Bordetella pertussis</italic> is a highly contagious respiratory pathogen, with infants at highest risk for severe infections. In 2005, the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) was licensed for use in nonpregnant adolescents and adults. Postpartum administration of Tdap to parents and other caregivers was encouraged to prevent the transmission of pertussis to newborns. In 2011, the Advisory Committee on Immunization Practices recommended that Tdap be administered at 20 weeks or greater to women who had not been previously vaccinated. In 2012, the committee recommended that Tdap be given to all parturients at 27 to 36 weeks, even if previously vaccinated. Whether vaccination with Tdap during pregnancy adversely affects the health of mothers or their offspring is unclear. This observational retrospective cohort study was performed to evaluate whether receipt of Tdap during pregnancy was associated with increased risks of adverse outcomes.</p> <p>Data, including birth weight and gestational age, were obtained on Tdap coverage for singleton pregnancies ending in a live birth during 2010 to 2012. Adverse outcomes were chorioamnionitis and hypertensive disorders of pregnancy. All hypertensive disorders of pregnancy were defined as those that had onset at 20 weeks' gestation or greater. Birth outcomes were preterm birth (<37 weeks) and small for gestational age (SGA; <10th percentile). For hypertensive disorders, women who received Tdap at less than 20 weeks' gestation were compared with women unexposed during pregnancy. For preterm delivery, analyses were limited to women receiving Tdap at 36 weeks' gestation or less. For chorioamnionitis and SGA births, all women who received Tdap during pregnancy were compared with all unexposed women. Risks of chorioamnionitis, SGA, and preterm births were also evaluated in a subset of women who received Tdap at 27 to 36 weeks compared with all women in the cohort who were unexposed to Tdap during pregnancy. All pregnancies were assigned a propensity score estimating their likelihood of receiving Tdap during pregnancy.</p> <p>Of 140, 343 pregnancies with singleton live births, 123, 494 were eligible, and 26, 229 (21.2%) of these received Tdap during pregnancy; 92% of vaccines were given during the second and third trimester. Among 97, 265 unexposed pregnancies, 46% received Tdap before pregnancy. At baseline, the largest difference between women who did or did not receive Tdap during pregnancy was receipt of another vaccine during pregnancy (53.8% of Tdap exposed vs 36.3% of unexposed). Propensity score C statistics indicated that baseline factors were not strongly associated with vaccination. Among women who received Tdap at any time during pregnancy, 6.1% had chorioamnionitis compared with 5.5% of unexposed women. After adjusting for site, receipt of other vaccines in pregnancy and the propensity score, the adjusted relative risk (aRR) for chorioamnionitis was 1.19 (95% confidence interval [CI], 1.13–1.26). In the subset of women vaccinated at 27 to 36 weeks' gestation, the aRR for chorioamnionitis was 1.11 (95% CI, 1.03–1.21). Among preterm births, the aRR of chorioamnionitis was 0.87 (95% CI, 0.64–1.16). Among women with and without chorioamnionitis, the median gestational weeks of vaccination were 28 weeks (interquartile range, 21–34 weeks) and 28 weeks (interquartile range, 21–33 weeks), respectively. In women receiving Tdap at less than 20 weeks, 8.2% developed a hypertensive disorder of pregnancy compared with 8.0% of unexposed women (aRR, 1.09; 95% CI, 0.99–1.20). Receipt of Tdap during pregnancy was not associated with increased risk of preterm or SGA births. Among all pregnancies, 8.4% of those who received Tdap during pregnancy and 8.3% who were unexposed had an SGA birth (aRR, 1.00; 95% CI, 0.96–1.06). The rates of preterm delivery among women receiving Tdap at 36 weeks' gestation or less or being unexposed were 6.3% and 7.8%, respectively (adjusted hazard ratio, 1.03; 95% CI, 0.97–1.09). The preterm delivery rate was 5.3% among women vaccinated at 27 to 36 weeks' gestation compared with 7.8% among the unvaccinated cohort. These differences were statistically significant (adjusted hazard ratio, 0.88; 95% CI, 0.80–0.95).</p> <p>Vaccination with Tdap during pregnancy was not associated with increased risks of preterm delivery or SGA birth or with maternal hypertensive disorders. A small but statistically significantly increased risk of chorioamnionitis was noted.</p> </sec> </abstract>