the great public health mysteries is why asthma has become more common among children, even as air pollution has decreased and fewer parents are smoking. One possibility is that antibiotics have kept infants' immune systems from developing properly, making them vulnerable to asthma and allergies later on. The Yale study, published in the American Journal of Epidemiology, supports this hypothesis.Researchers found that infants treated with antibiotics in their first six months were up to 52 percent more likely to develop asthma and allergies by age 6 than babies who did not get antibiotics. This result buttressed scientists' suspicion that early use of the drugs can cause imbalances in the immune system and a poor allergic response. Boston Globe
