Antibiotic use during pregnancy may up risk of childhood asthma
Frequent use of antibiotics during pregnancy is associated with an increased risk of childhood asthma, with the risk varies by timing and number of antibiotic courses used during pregnancy, according to a study presented at ATS 2018.
“Timing of antibiotic use appears to be important with early pregnancy use [being] associated with higher childhood asthma risk,” said Dr Kedir Turi of Vanderbilt University Medical Center in Nashville, Tennessee, US.
Although maternal antibiotic use across all trimesters was associated with an increased risk of childhood asthma, the researchers found that the later mothers started their first course of antibiotics during pregnancy, the lower the risk of their children developing asthma (173 days vs 41 days, adjusted odds ratio [OR], 0.80, 95 percent confidence interval [CI], 0.75–0.86). [ATS 2018, abstract A4194]
However, the association appears to be reversed after 200 days of gestational age, with later antibiotic use (from 200 days onwards) being positively associated with increased childhood asthma risk.
The risk of developing childhood asthma also rose with increasing number of maternal antibiotic courses used during pregnancy in a dose-dependent manner. Compared with children whose mothers did not use any antibiotics during pregnancy, those whose mothers used two courses of antibiotics were 30 percent more likely to develop asthma between age 4.5–6 years.
In addition, maternal antibiotic use during the first trimester only or during more than one trimester was associated with an 11 percent (OR, 1.11, 95 percent CI, 1.03–1.19) and 13 percent (OR, 1.13, 95 percent CI, 1.03–1.24) increased risk of developing childhood asthma, respectively, after adjustment for the number of antibiotic courses and covariates.
There was no significant association between the types of antibiotics used (broad- vs narrow-spectrum) and risk of childhood asthma. Broad-spectrum antibiotics are more commonly prescribed (91 percent) during pregnancy.
The retrospective population-based cohort study involved 84,880 mother-child pairs enrolled in the Tennessee Medicaid Program. Healthy children (52 percent male) who were born to term with non-low birth weight were considered eligible. Childhood asthma was assessed at age 4.5–6 years. By age 6, 14 percent of the children had developed asthma. Sixty-six percent of the mothers had ≥1 antibiotic course during pregnancy.
“The mechanisms through which antibiotics lead to increased asthma need to be understood to be able to develop effective prevention strategies,” said Turi.
According to Turi, some possible reasons which could explain the association between maternal antibiotic use and childhood asthma include: antibiotics may be an indicator of infection, a marker of genetic predisposition for asthma, and that antibiotic use during pregnancy may change the mother's and child's microbiome.