Women whose children are at risk for developing asthma should avoid antibiotics to the extent that they can, a study published in the Annals of Allergy, Asthma and Immunology reports.

The study followed 298 mother-child pairs through the child’s 3rd year from 1998 through 2009 in urban Chicago. Of the 103 children born to mothers who took antibiotics during pregnancy, 22% were diagnosed with asthma by age 3 compared with 11% of children born to mothers who did not take antibiotics during pregnancy. Analyses on the timing of prenatal antibiotic use showed a consistent relationship with use later in pregnancy, but outcomes were not associated with antibiotic use in the first trimester.

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Researchers recommend caution in prescribing antibiotics to pregnant women when symptoms are not clearly caused by a bacterial infection. Prenatal antibiotic use, however, was not associated with the development of wheezing.

For more information visit ACAAI.org.