By Rob Goodier

November 27, 2016

NEW YORK (Reuters Health) - New research confirms that children whose mothers used antibiotics during pregnancy have higher rates of asthma, but it remains unclear if the drugs or the infection, or something else entirely, is to blame.

Dr. Sandhya Vethachalam of Bronx-Lebanon Hospital Center in New York City and colleagues retrospectively analyzed the charts of more than 12,000 children and mothers. They found that 22.2% of mothers had infections during pregnancy, most often urinary tract infection during the first two trimesters.

Antibiotics use in pregnancy use was associated with 89% greater odds of the child developing asthma (p<0.0001), Dr. Vethachalam told Reuters Health by email. However, there was no significant association with the specific type of infection or antibiotic.

The findings were presented November 13 at the American College of Allergy, Asthma and Immunology annual conference in San Francisco, California.

Dr. Vethachalam said the cause of the association may have to do with the fetal microbiome: "Use of antibiotics by the mother will lead to fetal microbiome dysbiosis and can potentially remove the protective bacteria such as Lactobacillus, Bacteroides, and Bifidobacterium. This leads to Th1-Th2 imbalance and leads to atopic diseases in the child."

Dr. Myron Zitt, director of the Adult Allergy Clinic at Nassau University Medical Center in East Meadow, New York, cautioned that it is not clear whether the increased asthma risk is due to the infection or the antibiotics.

However, the new work confirms earlier studies tying childhood asthma to maternal use of antibiotics in pregnancy, he said, "in that the use of any antibiotic during pregnancy can potentially alter the maternal and placental microflora and can change the microbiome of infants, altering their immune system to predispose them to asthma and other allergic diseases."

The take-home message in this work should be a reminder to discourage the inappropriate use of antibiotics, Dr. Zitt told Reuters Health by email.

The researchers are now analyzing treated and untreated infections separately to try to untangle the individual roles of antibiotics use and infections.


American College of Allergy, Asthma and Immunology Annual Meeting 2016.