Could a routine pregnancy vaccine influence breastfeeding and baby health? a massive study digs into the data.
NCT ID NCT07735767
First seen Jul 30, 2026 · Last updated Jul 31, 2026 · Updated 1 time
Summary
This large study looks back at medical records of over 36,000 mother-infant pairs to see if receiving the Tdap vaccine during pregnancy or shortly after birth is linked to infant growth, how often babies need doctor or emergency visits, and whether mothers start or continue breastfeeding. The goal is to better understand any possible effects of the vaccine on these lactation-related outcomes.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Tdap vaccine (tetanus, diphtheria, acellular pertussis)
- What this could lead to
- If clear patterns emerge, this could help guide vaccination timing to support infant health and breastfeeding success.
- What could go wrong
- This is an observational study using existing records, so it can show links but cannot prove cause and effect. Results may be influenced by other factors not accounted for.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Participants
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36,245 people
The number who actually took part.
- Started
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Jan 2014
- Finished
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Dec 2022
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
Who is studied
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).
- Ages
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16 to 49 years
- Sex
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Female participants only
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 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. Exclusion Criteria: 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.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
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