The findings -- which may provide some reassurance to parents with general concerns about vaccination safety -- are reported in the May 7 issue of the Journal of the American Medical Association.
The new preliminary study explored the safety of the "Tdap" vaccine when offered before birth.
The investigation was prompted by the particular threat to infants posed by pertussis -- commonly known as whooping cough -- a highly contagious and sometimes deadly disease that has recently made a comeback among American children.
About 90 percent of fatal cases of whooping cough occur among children under the age of 6 months, according to background information from the journal.
However, although the disease is preventable if vaccinated against, current recommendations advise that the "DTaP" vaccine -- a different form of the vaccine used to prevent the same conditions -- be offered only to infants at the ages of 2 months, 4 months and 6 months.
This leaves open a potential window of risk between the time of birth and the first dose of DTaP, in which the newborn infant is not protected.
To cope with that window, researchers focused on the notion of vaccinating pregnant women. In theory, this would prompt mothers-to-be into developing pertussis antibodies that would, in turn, protect the fetus and, ultimately, the newborn.
The research team, led by Dr. Flor Munoz, at Baylor College of Medicine in Houston, followed 48 pregnant women. Of these, 33 were given the Tdap vaccine during their third trimester. The other 15 received a placebo (sham) vaccine.
No unexpected adverse reactions were observed among the mothers who were inoculated, or among their children. In addition, growth and development was similar among infants whose mothers were vaccinated during pregnancy compared to those whose mothers were not, according to a journal news release.
Children born to mothers who were vaccinated while pregnant were found to have much higher levels of pertussis antibodies in their systems than children whose mothers weren't -- both at birth and again at age 2 months -- the time of each infant's own first inoculation.
The authors noted that further research will be needed to confirm the safety and effectiveness of Tdap vaccination during pregnancy. The new study findings will also be presented at the annual meeting of the Pediatric Academic Societies, held in Vancouver.
To learn more about the Tdap vaccine, visit the U.S. Centers for Disease Control and Prevention.