Tdap Vaccine Was Safe Overall for Mom and Fetus

Tdap vaccine for pregnant moms did not increase premature birth or high blood pressure disorders during pregnancy in recent study

(RxWiki News) Since 2012, the Centers for Disease Control and Prevention (CDC) has suggested that all pregnant women receive the Tdap vaccine, even if they were vaccinated earlier in life. And new research found that Tdap was safe for both mom and baby.

The new study found that the vaccine did not cause many pregnancy issues and may prevent potentially deadly infectious diseases in newborns.

The study authors said all pregnant women should receive the vaccine, which prevents tetanus, diphtheria and pertussis (Tdap). A baby is more likely to become sick if its mother has an infectious disease, the authors noted.

All three of the diseases Tdap prevents are bacterial infections. Tetanus can affect the nervous system, and diphtheria and pertussis are respiratory infections. Pertussis is often known as whooping cough because the cough these patients have often has a distinct whooping sound.

The research was led by Elyse O. Kharbanda, MD, MPH, of the Health Practices Institute for Education and Research in Minneapolis, MN.

“[Giving] Tdap vaccinations routinely is a relatively recent recommendation," said Andre F. Hall, MD, an OB-GYN at Birth and Women's Care in Fayetteville, NC. "In my practice I offer Tdap to all pregnant patients at about 28 weeks [of pregnancy]. The concern primarily is 'whooping cough' or pertussis. Most babies who get pertussis get it from their mother. Vaccination of the mother during pregnancy reduces this incidence which can be life threatening for a baby.”

This study aimed to assess the safety of the Tdap vaccine for pregnant women and their babies. The researchers looked at common pregnancy conditions. They found that the vaccine was not more likely to make a woman go into early labor. It also did not cause pregnant women to have high blood pressure or preeclampsia. Preeclampsia is marked by a pregnant women having proteins in her urine and high blood pressure.

The vaccine did, however, increase the risk for chorioamnionitis — a bacterial infection of the membranes around the fetus. But this risk was small, the study authors found. Chorioamnionitis can cause some women to be in labor for an extended period of time or to go into labor early because of the infection. If this occurred, it would likely be due to this unusual infection — not a direct result of the vaccine, the authors noted.

The CDC recommends that women receive the vaccine when they are 27 to 36 weeks pregnant. These weeks are when vaccine is thought to be safest and most effective.

Dr. Kharbanda and team studied 123,494 pregnant women between Jan. 1, 2010, and Nov. 15, 2012, at two major health centers in California. Data about the women and the pregnancies was recorded in the California Vaccine Safety Datalink — a joint effort between the CDC and nine large US health care organizations.

Of the women, 26,229 had received the Tdap vaccine and 97,265 had not.

The women who received the vaccine were no more likely than those who were not vaccinated to give birth before 37 weeks of pregnancy. They also didn't have a raised risk of having an underweight baby.

Women who received the vaccine also didn't have a raised risk for high blood pressure during pregnancy.

The vaccinated women did, however, have a slightly raised risk for chorioamnionitis. They had a 6.1 percent chance of having the condition. Women who were not vaccinated had a 5.5 percent chance.

Women who received the vaccine 27 to 36 weeks into their pregnancy had a lower risk of chorioamnionitis than those who received it earlier — 5.6 percent.

Dr. Hall said he has “not found an increased rate of chorioamnionitis [among vaccinated women] and while this condition can be serious in the right circumstance, I feel the risk of pertussis poses a greater danger.”

The study authors said that, overall, the vaccine was safe.

“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,” Dr. Kharbanda and colleagues wrote.

This study was published online Nov. 12 in JAMA.

The CDC funded the study. Several of the study authors disclosed conflicts of interest. For instance, Nicola P. Klein, MD, PhD, received grant support from GlaxoSmithKline and Pfizer. T. Craig Cheetham, PharmD, received research support from Merck.


Review Date: 
November 11, 2014