Is the Tdap (Tetanus, diphtheria, and pertussis) vaccine safe for pregnant individuals?

Tdap Vaccine Safety in Pregnancy

Yes, the Tdap vaccine is safe for pregnant individuals and is strongly recommended during each pregnancy, ideally between 27-36 weeks gestation. 1

Safety Profile

The evidence overwhelmingly supports the safety of Tdap vaccination during pregnancy for both mother and infant. Large-scale studies from the United States and internationally have found no increased risk of adverse pregnancy outcomes, including: 1

• No increase in major malformations
• No increase in stillbirth
• No increase in preterm birth
• No increase in small for gestational age infants
• No increase in hypertensive disorders

Tetanus toxoid-containing vaccines have been used extensively in pregnant women worldwide for decades to prevent neonatal tetanus, with large studies reporting no clinically significant severe adverse events. 1

Common Side Effects

The most frequently reported reactions are mild and localized: 2

• Injection site reactions occur in approximately 79% of pregnant women receiving Tdap, which is comparable to postpartum vaccination rates 2
• Systemic symptoms (such as mild fever, fatigue, or body aches) occur in approximately 36% of pregnant women 2
• Fever is reported in only 1.7-6.8% of recipients 1

No serious adverse events have been documented in clinical trials of Tdap administration during pregnancy. 2

Theoretical Concerns Addressed

A theoretical risk exists for severe local reactions (Arthus reactions or whole limb swelling) in women receiving multiple closely spaced doses, but this concern is largely mitigated by modern vaccine formulations. 1

• Historical data on older tetanus toxoid formulations showed hypersensitivity reactions with multiple doses 1
• Current vaccine formulations contain lower doses of tetanus toxoid, substantially reducing this theoretical risk 1
• Studies of closely spaced doses (within 2 years) in non-pregnant individuals found no serious adverse events 1

The Advisory Committee on Immunization Practices (ACIP) concluded that experience with tetanus toxoid-containing vaccines suggests no excess risk for severe adverse events among women receiving Tdap with each pregnancy. 1

Repeat Vaccination Safety

Tdap should be administered during each pregnancy, regardless of prior vaccination history, because maternal antibodies wane rapidly. 3, 4

• Studies show no increased risk of adverse events in women who received a prior tetanus-containing vaccine ≤5 years before Tdap during pregnancy compared to those vaccinated >5 years prior 1
• The benefit of preventing pertussis morbidity and mortality in infants outweighs any theoretical concerns about repeat vaccination 1, 5

Maternal and Infant Benefits

Maternal Tdap vaccination is 80-91% effective in preventing pertussis in newborns and 58% effective in preventing hospitalization among infected infants. 3

• Infants born to vaccinated mothers have significantly higher pertussis antibody concentrations at birth (68.8 EU/mL vs 14.0 EU/mL in unvaccinated controls) 2
• These protective antibodies persist through the first 2 months of life, covering the period of greatest vulnerability before the infant's own vaccination series begins 2
• Maternal vaccination does not interfere with infant responses to their own DTaP vaccine series 2

Optimal Timing

Vaccination between 27-36 weeks gestation is recommended, with earlier timing in this window (27-32 weeks) preferred to maximize antibody transfer. 3, 4

• Active transport of maternal IgG antibodies does not substantially occur before 30 weeks gestation 1
• A minimum of 2 weeks is required to mount maximal immune response after vaccination 1
• Tdap may be safely administered at any time during pregnancy if needed for wound management or outbreak situations 1, 4

Clinical Pitfalls to Avoid

• Do not skip Tdap during pregnancy based on recent prior vaccination - it should be given with each pregnancy regardless of interval 3, 4
• Do not delay vaccination beyond 36 weeks - earlier administration within the recommended window optimizes antibody transfer 3
• Do not withhold vaccination due to concerns about repeat dosing - safety data support administration with each pregnancy 1, 5

Contraindications

The only true contraindications are: 3

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

A history of well-controlled seizures or family history of seizures is NOT a contraindication. 1