"In  as whooping cough continued its deadly comeback the U.S. Centers for Disease Control and Prevention  recommended that women get vaccinated against the bacterial infection during each pregnancy. A new CDC study finds that the preventive measure works. The vaccine http called Tdap tetanus diphtheria and pertussis cut the risk of whooping cough or pertussis by  percent in babies younger than two months whose mothers got inoculated in their third trimester of pregnancy. The study published Thursday in Clinical Infectious Diseases used data from  through  on babies younger than two months from six states. Among babies who developed whooping cough despite their mothers vaccination  percent had mild cases and did not require hospitalization. While the latest findings are heartening only about half of pregnant women in the U.S. are getting the vaccine the CDC said. Babies cannot be vaccinated against whooping cough until theyre  months old. The respiratory illness induces such uncontrollable fits of coughing that it can be deadly for babies who can stop breathing have seizures develop pneumonia or suffer brain damage. Pediatrician Paul A. Offit a vaccine expert  http Childrens Hospital of Philadelphia said Babies under  months old are only going to be protected by their mother who passes antibodies on to the child. So we have to do a better job of educating women. I think obstetricians can do a better job too. Women have such a great opportunity to help protect their babies before they enter the world by getting Tdap Nancy Messonnier director of the CDCs center for immunization and respiratory diseases said in a news release. This study reinforces CDCs recommendation. Before the introduction of whooping cough vaccine http_kidsHereswhythefluandwhoopingcoughvaccinesareimportant.html in the s more than  cases a year were reported in the U.S. By  that number plummeted to fewer than  a year. But the disease made a comeback in the s as the newer acellular https vaccine  containing only cellular material but not whole cells  was phased in. While it is safer and has fewer side effects than the old version studies have found that its protective effects wane more quickly http_Local_whooping_cough_cases_could_be_sign_of_weaker_vaccine.html than originally expected. Each year since  tens of thousands of cases of whooping cough have occurred and up to  babies have died. So far this year more than  cases have been reported."