Antibiotic use in babies linked to asthma

Infants given antibiotics during the first six months of life are more likely to develop asthma, according to a U.S. study.

Other studies have blamed antibiotics for rising rates of asthma in the developed world. Most were based on interviews with parents after their children were grown.

Instead of relying on parents' recall, Christine Cole Johnson, a senior research epidemiologist at Henry Ford Hospital in Detroit, followed 445 children from birth to age seven.

The children, half male and half female, received regular check-ups. At age six or seven, a certified allergist did skin tests to see if children were hypersensitive to an allergy-causing protein.

Nearly half were given antibiotics, usually penicillin, before six months of age.

The researchers found overall the children who received antibiotics by six months were 2.6 times more likely to develop allergic asthma, a condition triggered by environmental factors such as ragweed.

The research was reported on Tuesday at a meeting of the European Respiratory Society in Vienna.

Johnson said she isn't suggesting children should never be given antibiotics. Rather, she says doctors should be more prudent about prescribing them to young children.

"In the past, many of them were prescribed unnecessarily, especially for viral infections like colds and the flu, when they would have no effect anyway," she said in a release.

Johnson speculates antibiotics may change the bacteria growing in the gut and disrupt the developing immune system.

According to the hygiene hypothesis, exposure to animal dander, ragweed and dirt may help protect kids' immune systems.

The idea is the germs may mature the immune system against allergies, much like vaccines protect us from disease.

The researchers also found having fewer than two pet cats and dogs, or a mother with asthma seemed to increase the risk of allergy for a child popping antibiotics.

Teasing out any possible relationship remains a problem, though. It may be the infections rather than the antibiotics triggering the asthma.