PURPOSE OF THE STUDY.
The purpose of this study was to explore associations between prenatal and postnatal exposure to antibiotics and the risk of childhood asthma.
All children born in Finland between 1996 and 2004 and diagnosed with asthma and 1 matched control per case were identified from 4 national health registries (Drug Prescription Register, Special Reimbursement Register, Population Register, and Medical Birth Register), resulting in 6690 case-control pairs.
Prenatal exposure to antibiotics was identified by extracting purchasing history of all antibiotics (ATC Code J01—antibiotics for systemic use) by the mother during pregnancy from the Drug Prescription Registry. Postnatal exposure to antibiotics was identified by extracting purchasing history of all antibiotics for the child from birth until the date of asthma diagnosis from the same Drug Prescription Registry. Maternal background and perinatal variables were also measured and include maternal age, maternal asthma, smoking during pregnancy, socioeconomic status, previous deliveries, previous miscarriages, mode of delivery, and gestational age and birth weight/birth length. Logistic regression was used to identify associations between maternal background and perinatal factors and the use of antibiotics in pregnancy and during the first 3 years of life in the control group. Conditional logistic regression was used to analyze associations between maternal and child use of antibiotics and the risk of asthma diagnoses in the case group.
Maternal use of antibiotics during pregnancy, particularly cephalosporins, macrolides, extended spectrum penicillins, and phenoxymethylpenicillin, was associated with an increased risk of asthma in the child [adjusted odds ratio = 1.31 (95% confidence interval, 1.21–1.42)]. Antibiotics administered during the first year of life also increased the risk of asthma [adjusted odds ratio = 1.60 (95% confidence interval, 1.48–1.73)].
Both prenatal and postnatal exposure to antibiotics was associated with an increased risk of developing childhood asthma. A dose-related response was observed in this analysis of large population and registry based data sets.
This study used data from the Finnish national health registry. Because of that country’s socialized medical system, this mitigates bias in patient selection, access to health care, cost of treatment, and social determinants. Although wheezing is common in children, this cohort used strict diagnostic criteria to identify asthmatic patients and accurately documented the administration of asthma medications. All prenatal and postnatal antibiotics were captured, eliminating the recall bias often seen in other studies that examine the role of antibiotics on the development of asthma. Prenatal antibiotic use changes the vaginal flora, thus altering the initial colonizing bacteria for the infant. It is also postulated that antibiotics profoundly affect the symbiotic relationship between gut flora and the immune system, ultimately modifying the nature and intensity of the human immune response. The combination of these 2 factors may lead to the immunologic changes that lead to asthma.
- Copyright © 2015 by the American Academy of Pediatrics