Administration of Tdap vaccine during pregnancy not linked with preterm delivery

November 11, 2014

Among approximately 26,000 women, receipt of the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine during pregnancy was not associated with increased risk of preterm delivery or small-for-gestational-age birth or with hypertensive disorders of pregnancy, although a small increased risk of being diagnosed with chorioamnionitis (an inflammation of the membranes that surround the fetus) was observed, according to a study in the November 12 issue of JAMA.

The Tdap vaccine was licensed in 2005 for use in nonpregnant adolescents and adults. Initially, postpartum administration of Tdap to parents and other caregivers was encouraged to prevent the transmission of pertussis to newborns. However, recent outbreaks, including infant deaths, have led to changing Tdap vaccine recommendations. In 2010, California became the first state to recommend Tdap be routinely administered during pregnancy. Tdap is now recommended by the Advisory Committee on Immunization Practices for all pregnant women, preferably between 27 and 36 weeks' gestation. To date, there have been limited specific data on whether vaccination with Tdap during pregnancy adversely affects the health of mothers or their offspring, according to background information in the article.

Elyse O. Kharbanda, M.D., M.P.H., of the HealthPartners Institute for Education and Research, Minneapolis, and colleagues used administrative health care databases from 2 California Vaccine Safety Datalink sites to examine whether receipt of Tdap during pregnancy was associated with increased risks of selected adverse obstetric or birth outcomes. Included in the analysis were 123,494 women with pregnancies ending in a live birth between January 1, 2010 and November 15, 2012; 26,229 (21 percent) received Tdap during pregnancy and 97,265 did not.

The researchers found that receipt of Tdap during pregnancy was not associated with increased risk of preterm (<37 weeks' gestation) or small-for-gestational-age (SGA) births. Among all pregnancies, 8.4 percent of those who received Tdap during pregnancy and 8.3 percent who were unexposed to the vaccine had an SGA birth. The rate of preterm delivery among women receiving Tdap during pregnancy at 36 weeks' gestation or earlier was 6.3 percent, whereas the rate for unexposed women was 7.8 percent. Receipt of Tdap was not associated with increased risk of hypertensive disorders of pregnancy.

Among women who received Tdap at any time during pregnancy, 6.1 percent were diagnosed with chorioamnionitis compared with 5.5 percent of unexposed women. In the subset of women vaccinated between 27 and 36 weeks' gestation, this risk was still increased but less so. The authors note that these results should be interpreted with caution because the magnitude of the risk was small.

"Given limited prior safety data, continued widespread pertussis transmission, and current recommendations to routinely vaccinate during pregnancy, our study provides important information on the safety of Tdap vaccination during pregnancy," the authors write.
(doi:10.1001/jama.2014.14825; Available pre-embargo to the media at

Editor's Note: This study was funded through a contract from the CDC. Additional funding for chart reviews came from contracts from the CDC Vaccine Safety Datalink infrastructure task order. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, etc.

The JAMA Network Journals

Related Pregnancy Articles from Brightsurf:

COVID-19 has a prolonged effect for many during pregnancy
Symptoms for pregnant women with COVID-19 can be prolonged, lasting two months or longer for a quarter of the women who participated in a national study led by UC San Francisco and UCLA.

Relaxed through pregnancy
A group of researchers from Charité - Universitätsmedizin Berlin have been able to show that maternal psychological wellbeing during pregnancy has a positive effect on newborn infants.

Trajectories of antidepressant medication use during pregnancy
In an analysis of women who started pregnancy when taking antidepressant medications, investigators identified three trajectories of antidepressant dispensing during pregnancy: more than half stopped their treatment, a quarter maintained their treatment throughout pregnancy, and one-fifth discontinued it for a minimum of three months and then resumed it during the postpartum period.

Are women using e-cigarettes during preconception and/or pregnancy?
A new study of 1,365 racially/ethnically diverse, low-income pregnant women found that 4% reported e-cigarette use.

A better pregnancy test for whales
To determine whale pregnancy, researchers have relied on visual cues or hormone tests of blubber collected via darts, but the results were often inconclusive.

Cannabis use during pregnancy
The large health care system Kaiser Permanente Northern California provides universal screening for prenatal cannabis use in women during pregnancy by self-report and urine toxicology testing.

Questions and answers about cannabis use during pregnancy
A new study shows that women have many medical questions about the use of cannabis both before and during pregnancy, and during the postpartum period while breastfeeding.

The effect of taking antidepressants during pregnancy
Exposure to antidepressants during pregnancy and the first weeks of life can alter sensory processing well into adulthood, according to research in mice recently published in eNeuro.

Is ivermectin safe during pregnancy?
Is it safe to give ivermectin to pregnant women? To answer this question, researchers from the Barcelona Institute for Global Health (ISGlobal), an institution supported by 'la Caixa,' conducted a systematic review and meta-analysis of studies that reported cases of accidental exposure to the drug among pregnant women.

Going to sleep on your back in late pregnancy
This study looked at whether going to sleep on your back in the third trimester of pregnancy was associated with average lower birth weights.

Read More: Pregnancy News and Pregnancy Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to