The purpose of this study is to evaluate the safety of Adacel vaccine among pregnant individuals exposed to Adacel at any point between the 1st day of the 27th week of gestation up to the end of pregnancy and their offspring (ie, Adacel-exposed cohort), in comparison with pregnant individuals not vaccinated with any Tdap vaccines during pregnancy and their offspring (ie, Tdap-unvaccinated comparator cohort). The primary objectives are to estimate incidence rates and relative risks for each prespecified pregnancy outcome in Adacel-exposed and Tdap-unvaccinated comparator cohorts and for each prespecified adverse birth outcome in the offspring of both cohorts. The secondary objectives are to estimate incidence rates and relative risks for each prespecified adverse fetal and neonatal outcome in the offspring of Adacel-exposed and Tdap unvaccinated comparator cohorts and for each prespecified adverse outcome for pregnant individuals in both cohorts.
This is a retrospective cohort study utilizing existing EHR data to identify eligible pregnant individuals, with an observation period spanning January 2016 through December 2024. Given this study design, follow-up for all pregnancies with documented deliveries is expected to be complete by December 2025. The study report is expected to be completed by 31 December 2026.
Study Type
OBSERVATIONAL
Enrollment
365,000
Not applicable / database analysis
Investigational Site
Chilly-Mazarin, France
Pregnancy outcome: Live birth
Incidence rates of live births in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Pregnancy outcome: Still birth/fetal demise
Incidence rates of still birth/fetal demise in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Pregnancy outcome: Therapeutic abortion
Incidence rates of therapeutic abortion in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Birth outcome: Preterm birth
Incidence rates of preterm birth in live born infants of both Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation and less than 37 weeks gestation
Birth outcome: Low birth weight
Incidence rates of low birth weight in live born infants of both Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Birth outcome: Small for gestational age
Incidence rates of small for gestational age in live born infants of both Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Adverse neonatal outcome: Neonatal death
Incidence rates of neonatal death in the offspring of Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From birth up to 28 days post-birth
Adverse neonatal outcome: Neonatal sepsis
Incidence rates of neonatal sepsis in the offspring of Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From birth up to 28 days post-birth
Adverse neonatal outcome: Neonatal respiratory distress
Incidence rates of neonatal respiratory distress in the offspring of Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From birth up to 28 days post-birth
Adverse neonatal outcome: Congenital anomalies
Incidence rates of congenital anomalies (major and minor) in the offspring of Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From birth up to 28 days post-birth
Adverse neonatal outcome: Neonatal/early infancy intensive care admissions for bronchopulmonary dysplasia
Incidence rates of neonatal/early infancy intensive care admissions for bronchopulmonary dysplasia in the offspring of Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From birth up to 28 days post-birth
Adverse fetal outcome: Fetal growth arrest (restriction)
Incidence rates of fetal growth arrest (restriction) in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Adverse outcomes in pregnant individuals: Preterm labor
Incidence rates of Preterm labor in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation and less than 37 weeks gestation
Adverse outcomes in pregnant individuals: Preeclampsia/eclampsia
Incidence rates of preeclampsia/eclampsia in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 days postpartum
Adverse outcomes in pregnant individuals: Postpartum hemorrhage
Incidence rates of postpartum hemorrhage in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: Within 24 hours of delivery up to 28 days postpartum
Adverse outcomes in pregnant individuals: Placental abruption
Incidence rates of placental abruption in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Adverse outcomes in pregnant individuals: Premature rupture of membranes
Incidence rates of premature rupture of membranes in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
Adverse outcomes in pregnant individuals: Chorioamnionitis
Incidence rates of chorioamnionitis in Adacel-exposed and Tdap-unvaccinated comparator cohorts
Time frame: From 1st day of the 27th week of gestation up to 42 weeks gestation
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