Tdap Vaccination During Pregnancy or Postpartum and Lactation-Related Outcomes

NCT07735767 | Completed FDA Drug

• 1 other identifier: Td500060
• Study Type: observational
• Target: 36,245
• Locations: 0 countries
• Sites: N/A

Brief Summary

A retrospective cohort study based on the secondary use of pre-existing data. The study assesses the association between antenatal and postpartum maternal Tdap vaccination and select infant and lactation-related outcomes.

Conditions

Pertussis Vaccines

Keywords

Tdap; Pregnancy; Postpartum; Lactation; Infant; Electronic Health Record; Breastfeeding

Outcome Measures

Primary Outcomes (15)

• Infant growth - failure to thrive (Subgroup Pregnancy)

  Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy and up to 90 days after delivery

  3 months (91 days) to 12 months of age

• Infant growth - failure to thrive (Subgroup Postpartum)

  Among patients who did not discontinue human milk feeding on or before 90 days after delivery. Exposure: Any Tdap 0 to 90 days after delivery Comparator: No Tdap 0 to 90 days after delivery

  3 months (91 days) to 12 months of age

• Infant health care utilization - Number of infant outpatient visits up to 6 months of age (Subgroup Pregnancy)

  Count of unique dates of outpatient visits in the 6 months after delivery. Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy and up to 90 days after delivery

  0 to 6 months after delivery

• Infant health care utilization - Number of infant outpatient visits in the 90 days after index date (Subgroup Postpartum )

  Among patients who did not discontinue human milk feeding before index date (ie, vaccination or pseudovaccination date), count of unique dates of outpatient visits in the 90 days after vaccination or pseudovaccination. Exposure: Any Tdap 0 to 90 days after delivery Comparator: No Tdap 0 to 90 days after delivery

  up to 6 months: 90-day window for vaccination plus 90-day window for outcome assessment

• Infant health care utilization - Number of infant emergency department visits up to 6 months of age (Subgroup Pregnancy)

  Count of unique dates of emergency department visits in the 6 months after delivery. Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy and up to 90 days after delivery

  0 to 6 months after delivery

• Infant health care utilization - Number of infant emergency department visits in 90 days after index date (Subgroup Postpartum)

  Among patients who did not discontinue human milk feeding before index date (ie, vaccination or pseudovaccination date), count of unique dates of emergency department visits in the 90 days after vaccination or pseudovaccination. Exposure: Any Tdap 0 to 90 days after delivery Comparator: No Tdap 0 to 90 days after delivery

  Up to 6 months: 90-day window for vaccination plus 90-day window for outcome assessment.

• Human milk feeding initiation vs no initiation (Subgroup Pregnancy)

  Any or exclusive human milk versus formula only or no human milk feeding documented during follow up. Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy

  0 to 12 months

• Any human milk feeding vs none around the 2-month Well Child Visit (WCV) (Subgroup Pregnancy)

  Any human milk versus formula only or no human milk feeding documented 42 to 104 days after delivery Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy through 41 days after delivery

  42 to 104 days after delivery

• Any human milk feeding vs none around the 2-month WCV (Subgroup Postpartum)

  Among those patients who did not discontinue human milk feeding before Tdap vaccine receipt or before the outcome window of interest, any human milk versus formula only or no human milk feeding documented 42 to 104 days after delivery Exposure: Any Tdap 0 to 41 days after delivery Comparator: No Tdap during pregnancy through 41 days after delivery

  42 to 104 days after delivery

• Exclusive human milk feeding vs none around the 2-month WCV (Subgroup Pregnancy)

  Exclusive human milk feeding only versus formula, with or without human milk documented 42 to 104 days after delivery Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy through 41 days after delivery

  42 to 104 days after delivery

• Exclusive human milk feeding vs none around the 2-month WCV (Subgroup Postpartum)

  Among those patients who did not discontinue human milk feeding before Tdap vaccine receipt or before the outcome window of interest, exclusive human milk feeding only versus formula, with or without human milk documented 42 to 104 days after delivery Exposure: Any Tdap 0 to 41 days after delivery Comparator: No Tdap during pregnancy through 41 days after delivery

  42 to 104 days after delivery

• Any human milk feeding vs none around the 6-month WCV (Subgroup Pregnancy)

  Any human milk versus formula only or no human milk feeding documented 148 to 210 days after delivery Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy through 147 days after delivery

  148 to 210 days after delivery

• Any human milk feeding vs none around the 6-month WCV (Subgroup Postpartum)

  Among those patients who did not discontinue human milk feeding before Tdap vaccine receipt or before the outcome window of interest, any human milk versus formula only or no human milk feeding documented 148 to 210 days after delivery Exposure: Any Tdap 0 to 90 days after delivery Comparator: No Tdap 0 to 90 days after delivery

  148 to 210 days after delivery

• Exclusive human milk feeding vs none around the 6-month WCV (Subgroup Pregnancy)

  Exclusive human milk feeding only versus formula, with or without human milk documented 148 to 210 days after delivery Exposure: Tdap on or after 27 gestational weeks (ie, \> 188 days gestation) and less than delivery date Comparator: No Tdap during pregnancy through 147 days after delivery

  148 to 210 days after delivery

• Exclusive human milk feeding vs none around the 6-month WCV (Subgroup Postpartum)

  Among those patients who did not discontinue human milk feeding before Tdap vaccine receipt or before the outcome window of interest, exclusive human milk feeding only versus formula, with or without human milk documented 148 to 210 days after delivery Exposure: Any Tdap 0 to 90 days after delivery Comparator: No Tdap 0 to 90 days after delivery

  148 to 210 days after delivery

Secondary Outcomes (2)

• Infant growth - Rate of weight gain (Subgroup Pregnancy)

  3 - 9 months (To determine predicted values at 9 months of age, measurements up to 12 months were used)

• Infant growth - Rate of weight gain (Subgroup Postpartum)

  3 - 9 months (To determine predicted values at 9 months of age, measurements up to 12 months were used)

Study Arms (2)

Vaccine Group

Patients who received Tdap vaccine during pregnancy or up to 90 days postpartum.

Biological: Tetanus Toxoid, acellular pertussis, diphtheria toxoid

Unvaccinated Control Group

Patients who did not receive Tdap vaccine during pregnancy and/or up to 90 days postpartum.

Interventions

Tetanus Toxoid, acellular pertussis, diphtheria toxoid BIOLOGICAL

No investigational vaccines will be administered in this study. Participants will be included in the study on the basis of their having received Tdap vaccine as part of routine care.

Vaccine Group

Eligibility Criteria

• Age: 16 Years - 49 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)
• Sampling Method: Non-Probability Sample

Study Population

Retrospective cohort study using existing automated electronic health record (EHR) data from two large integrated health care delivery systems based in Hawaii (Kaiser Permanente Hawaii) and Minnesota (HealthPartners).

You may qualify if:

• The study includes pregnant women aged 16-49 years at delivery who had a live-birth delivery between 01 January 2014 (01 June 2018 for one site given data availability) and 31 December 2022, received prenatal care within the participating health systems before 6 months gestation, had a gestational age at delivery of at least 27 weeks, and linked to an infant with a WCV before 2 months of age within the participating health systems.

You may not qualify if:

• We excluded those with Tdap vaccination before the recommended gestational age of 27 gestational weeks. For postpartum analyses, we excluded those who did not initiate human milk feeding or where human milk feeding information was not available.

Sponsors & Collaborators

• HealthPartners Institute: lead
• Sanofi: collaborator
• Kaiser Permanente: collaborator

MeSH Terms

Conditions

Breast Feeding

Interventions

Tetanus Toxoid; Diphtheria Toxoid

Condition Hierarchy (Ancestors)

Feeding Behavior; Behavior

Intervention Hierarchy (Ancestors)

Toxoids; Vaccines; Biological Products; Complex Mixtures

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 24, 2026
• First Posted: July 30, 2026
• Study Start: January 1, 2014
• Primary Completion: December 1, 2022
• Study Completion: December 1, 2022
• Last Updated: July 30, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share