Prenatal, early pregnancy first course, and broad-spectrum antibiotic exposure may be associated with an increased risk for asthma in children, according to study results published in Clinical Infectious Diseases.

In this population-based cohort study, a total of 84,214 mother-child dyads of infants born between 1995 and 2003 who were continuously enrolled in the Tennessee Medicaid Program (TennCare) were included. Logistic regression analyses were used to examine the association between prenatal antibiotic exposure and childhood asthma. The number of antibiotic courses (range, 0-10), timing (trimester-specific effect, gestational age at the first course of prenatal antibiotic exposure), and spectrum (none, narrow only, broad only, and both) represented the main features of antibiotic exposure. In addition, researchers investigated the association between gestational age (in days) at the first prenatal antibiotic course and childhood asthma in children exposed to ≥1 prenatal antibiotic course.

Approximately 64% (n=54,141) of children were exposed to 104,082 prenatal antibiotic courses. The investigators found a dose-dependent association between prenatal antibiotic exposure and increased odds of childhood asthma (adjusted odds ratio [aOR] for interquartile increase of 2 courses [2 vs 0], 1.26; 95% 95%CI, 1.20-1.33). Exposure to an antibiotic course at 163 days gestational age vs early exposure at 40 days gestational age was associated with 19% decreased odds of childhood asthma (aOR, 0.81, 95% CI, 0.76-0.87). In addition, broad-spectrum-only antibiotic exposure was associated with increased asthma odds compared with narrow-spectrum-only antibiotics (aOR, 1.12; 95% CI, 1.02-1.24).

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The association between the number of prenatal antibiotic courses and the development of asthma was modified by maternal asthma (P <.001 for interaction analysis). The dose-dependent association between childhood asthma and the number of prenatal antibiotic courses persisted only in children with mothers who did not have asthma (2 vs 0 courses: aOR, 1.26; 95% CI, 1.20-1.33).

Study limitations were the lack of fathers’ asthma status and the lack of data on whether mothers took their antibiotics as prescribed.

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Considering antibiotics are commonly prescribed for women during pregnancy and asthma is a chronic disease, the investigators wrote that the “risks and benefits of prenatal antibiotic use, timing, and choice of antibiotics should be critically evaluated prior to administration.”

Disclosure: A study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Turi KN, Gebretsadik T, Ding T, et al. Dose, timing, and spectrum of prenatal antibiotic exposure and risk of childhood asthma [published online January 29, 2020]. Clin Infect Dis. doi:10.1093/cid/ciaa085