Is Tdap (Tetanus, diphtheria, and pertussis) vaccine safe in the third trimester of pregnancy?

From the Guidelines

Yes, the Tdap vaccine is safe during the third trimester of pregnancy. The CDC recommends that pregnant women receive the Tdap vaccine between 27 and 36 weeks of each pregnancy, regardless of their prior vaccination history, as stated in the most recent guidelines from 2018 1. This timing is optimal because it allows maternal antibodies to transfer to the baby, providing protection against pertussis (whooping cough) during the first few months of life when the infant is most vulnerable and before they can receive their own vaccinations. The vaccine contains tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis antigens. Side effects are generally mild and may include pain or swelling at the injection site, mild fever, headache, or fatigue, as reported in studies 1. These temporary discomforts are far outweighed by the protection provided to both mother and baby. Pertussis can be life-threatening for newborns, and vaccination during pregnancy has been shown to be effective in preventing the disease in babies, with recent reviews supporting the current recommendations 1.

Some key points to consider:

• The CDC and other health organizations recommend Tdap vaccination during the third trimester to optimize the transfer of maternal antibodies to the infant.
• The vaccine is safe for use in pregnant women, with no increased risk of adverse events or birth defects, as confirmed by multiple studies 1.
• Vaccination during pregnancy provides protection against pertussis for both the mother and the infant, reducing the risk of severe disease and death in newborns.
• The most recent guidelines and reviews support the use of Tdap vaccine in pregnant women, with no changes to the recommended timing or dosing 1.

Overall, the evidence supports the safety and effectiveness of Tdap vaccination during the third trimester of pregnancy, and healthcare providers should administer this vaccine to pregnant women between 27 and 36 weeks of gestation.

From the Research

Safety of Tdap Vaccination in the Third Trimester

• The safety of Tdap vaccination in the third trimester has been evaluated in several studies, with no evidence of adverse fetal effects from vaccinating pregnant women with inactivated virus or bacterial vaccines or toxoids 2.
• A study published in 2017 found that Tdap vaccination during pregnancy, particularly in the third trimester, was effective in preventing pertussis in infants, with a risk reduction of 85% compared to postpartum vaccination 3.
• Another study published in 2021 found that prenatal Tdap vaccination reduced the risk of pertussis infections in infants' first 6 months by 36%, with the greatest benefit seen in preterm infants 4.
• The Advisory Committee on Immunization Practices recommends that Tdap vaccine be administered during each pregnancy, ideally between 27 and 36 weeks of gestation, to maximize the maternal antibody response and passive antibody transfer and levels in the newborn 2.
• The National Advisory Committee on Immunization in Canada also recommends offering Tdap vaccine in every pregnancy, ideally between 27 and 32 weeks of gestation, but also supports providing maternal Tdap over a wider range of gestational ages 5.

Effectiveness of Tdap Vaccination in Preventing Pertussis

• Studies have consistently shown that Tdap vaccination during pregnancy is effective in preventing pertussis in infants, particularly in the first 6 months of life 3, 4.
• The effectiveness of Tdap vaccination in preventing pertussis has been estimated to be over 90% in infants younger than two months of age, with no deaths observed among infants whose mothers received Tdap prior to 36 weeks of pregnancy 5.
• Tdap vaccination during pregnancy has also been shown to reduce the severity of pertussis disease and hospitalization in infants 5.

Recommendations for Tdap Vaccination in Pregnancy

• The Advisory Committee on Immunization Practices recommends that Tdap vaccine be administered during each pregnancy, ideally between 27 and 36 weeks of gestation 2.
• The National Advisory Committee on Immunization in Canada recommends offering Tdap vaccine in every pregnancy, ideally between 27 and 32 weeks of gestation, but also supports providing maternal Tdap over a wider range of gestational ages 5.
• The American College of Obstetricians and Gynecologists also recommends that Tdap vaccine be administered during each pregnancy, ideally between 27 and 36 weeks of gestation, to minimize the risk of pertussis in newborns 2.