Prenatal and early-life exposure to antibiotics does not seem to cause asthma in children, according to large new study. “Our results indicate that there doesn’t seem to be a causal link between antibiotic treatment during pregnancy or early in life and childhood asthma,” lead author Dr. Anne Ortqvist of the Karolinska Institute in Stockholm told Reuters Health by email.  “Instead, we suggest that factors that are shared within families, such as genetic predisposition to respiratory infections and asthma, consultation patterns or other home and environmental factors, together with confounding by respiratory infections, have biased previous results.”

Given that the rise in antibiotic use occurred in tandem with increases in asthma prevalence in children, several observational studies have been conducted to evaluate whether the two are related, but results have been mixed, Dr. Ortqvist and her team write in their report, published online November 28 in BMJ. In the new study, the researchers sought to account for familial factors by using sibling controls. To address the possibility of confounding by indication and reverse causation, they examined whether specific antibiotic types were linked to asthma. They looked at more than 493,000 children born in 2006-2010, and identified nearly 181,000 who were eligible for sibling analyses.

While prenatal exposure to antibiotics overall was linked to an increased risk of asthma (hazard ratio, 1.28), sibling analyses did not find an association (HR, 0.99), the researchers found. The risk associated with asthma was more pronounced when looking at antibiotics used to treat respiratory infections (HR, 4.12) versus antibiotics used to treat urinary tract or skin infections in children (HR, 1.54). However, sibling analyses reduced the association for exposure to antibiotics for respiratory infections (HR, 2.36), and there was no significant association between the use of antibiotics for urinary tract or skin infections and asthma risk (HR, 0.85).

“Our study suggests that antibiotics do not cause asthma, however, considering the threat of antibiotic resistance worldwide it is of great importance that antibiotics are used carefully,” Dr. Ortqvist said. “So, if clinicians’ use of antibiotics should change in any way that would be to consider the necessity of treatment with antibiotics for each patient one more time before prescribing it.” She added: “We would like to emphasize the importance of correctly diagnosing children with respiratory symptoms, where suspected symptoms of asthma should be separated from respiratory infections, and treated according to guidelines. Also, as the majority of respiratory infections in young children are caused by viruses, the need of treatment with antibiotics in these children may be questioned.”

Dr. Ortqvist said she and her colleagues are planning to use Swedish population-based data to investigate whether early antibiotic exposure is associated with other childhood illnesses.

SOURCE: http://bit.ly/15SwB26

Dr. Kenneth Backman of Allergy & Asthma Care of Fairfield County comments: “There have been many studies trying to determine the causes and risk factors for childhood asthma. While early life antibiotics have been implicated in some smaller studies, this well designed study did not identify an association. Many studies continue to try to identify the cause of the increase in asthma and allergies in children and adults.”