CHICAGO, Oct 25: An advisory committee for the US Centers for Disease Control and Prevention voted yesterday to recommend that pregnant women be immunized against pertussis during each pregnancy in hopes of stemming a growing US outbreak of the illness, also known as whooping cough. Giving a booster shot during pregnancy increases the chances that antibodies from the mother will be passed along to her baby, offering the infant increased protection until the child is old enough be immunized, starting at two months. (agencies)