What are the guidelines for Td (tetanus and diphtheria) vaccine injection in pregnancy?

Td/Tdap Vaccination in Pregnancy Guidelines

Primary Recommendation

All pregnant women should receive Tdap vaccine between 27-36 weeks gestation during every pregnancy, regardless of prior vaccination history. 1, 2, 3

Optimal Timing and Rationale

Administer Tdap between 27-36 weeks gestation, preferably early in this window (27-32 weeks) to maximize maternal antibody transfer to the infant. 4, 2, 3

The biological rationale for this timing includes:

• Active transport of maternal IgG antibodies does not substantially occur before 30 weeks gestation, making earlier vaccination less effective for passive infant protection 1
• A minimum of 2 weeks is required after vaccination to mount maximal immune response, so vaccination must occur with sufficient time before delivery 1, 4
• Maternal antibodies wane rapidly—even women vaccinated in the first or second trimester show low antibody levels at term 1, 4
• Vaccination during the recommended 27-36 week window is 80-91% effective at preventing infant pertussis, compared to 85% more effective than postpartum vaccination alone 4, 2, 5

Vaccination with Each Pregnancy

Tdap must be administered during each pregnancy, even if the woman received Tdap previously, because antibody levels decline substantially within one year 1, 2, 3

This represents a critical shift from earlier "cocooning" strategies that focused on postpartum vaccination. The Advisory Committee on Immunization Practices updated this recommendation in 2013 based on evidence that maternal vaccination provides superior infant protection compared to postpartum vaccination alone. 1

Special Clinical Situations

Pregnant Women Due for Tetanus Booster

If a woman is due for routine tetanus-diphtheria booster (>10 years since previous Td), administer Tdap instead of Td between 27-36 weeks gestation. 1

Wound Management During Pregnancy

For wound management requiring tetanus prophylaxis (≥5 years since previous booster), administer Tdap regardless of gestational age. 1, 4

This takes precedence over the optimal timing window because immediate tetanus protection is medically necessary. 1

Unknown or Incomplete Tetanus Vaccination History

Women who have never been vaccinated against tetanus require a three-dose primary series:

• First dose: at initial presentation
• Second dose: 4 weeks after first dose
• Third dose: 6-12 months after first dose 1, 2

Tdap should replace one dose of Td in this series, preferably between 27-36 weeks gestation. 1, 2

This ensures both maternal protection against tetanus/diphtheria and optimal passive infant protection against pertussis. 1

Safety Profile

Inactivated vaccines like Tdap are safe during pregnancy, with no evidence of adverse fetal effects. 4, 3, 6

Key safety considerations:

• Large studies on tetanus toxoid use during pregnancy have not reported clinically significant severe adverse events 1
• Experience with tetanus toxoid-containing vaccines suggests no excess risk for severe adverse events when Tdap is given with every pregnancy 1, 4
• The potential benefit of preventing pertussis morbidity and mortality in infants outweighs theoretical concerns of adverse events 1, 4

The Advisory Committee on Immunization Practices has established ongoing safety monitoring through the Vaccine Adverse Event Reporting System and Vaccine Safety Datalink to continue assessing safety with repeated pregnancy doses. 1

Postpartum Administration

If Tdap was not administered during pregnancy, give it immediately postpartum before hospital discharge. 1, 7

However, this is suboptimal compared to prenatal vaccination because it does not provide passive antibody protection to the newborn during the highest-risk period (first 8 weeks of life when pertussis mortality is greatest). 3, 5

Common Clinical Pitfalls to Avoid

• Missing the 27-36 week window by delaying vaccination to postpartum period, which provides substantially less infant protection 4, 5
• Failing to vaccinate during each pregnancy based on misconception that prior Tdap provides adequate protection 2, 3
• Delaying Tdap when indicated for wound management due to concerns about gestational age 1, 4
• Not completing the primary series in women with unknown or incomplete vaccination history, leaving them vulnerable to maternal and neonatal tetanus 1
• Administering Td instead of Tdap when a tetanus booster is indicated during pregnancy, missing the opportunity for pertussis protection 1

Contraindications

The only absolute contraindications to Tdap are:

• Severe allergic reaction (anaphylaxis) after a previous dose or to a vaccine component 2
• Encephalopathy not attributable to another identifiable cause within 7 days of previous pertussis-containing vaccine 2

Pregnancy itself is not a contraindication to Tdap vaccination. 3, 6