Objectives: Recent research has suggested that the protective effect of natural infections may be due to their influence on the development of the immune system in early life. The purpose of the study was to determine whether maternal use of antibiotics during pregnancy is a risk factor for wheezing and allergy in early infancy.
Materials and methods: Nonsmoking women, aged 18-35 years, were enrolled in 2000/2001 from prenatal clinics during the second or third trimester of pregnancy. After delivery, newborns were followed-up every three months over one year and trained interviewers conducted a standardized interview with mothers on infants' health at each visit held every three-month. In total, 102 infants were followed over a one-year period and questionnaires on the use of various medications during pregnancy and potential risk factors for allergy and asthma were completed. Relative risk for persistent wheezing (9+ days over the follow-up) adjusted for potential confounders was significantly associated with the duration of antibiotic therapy, however, it was significant only if the antibiotic treatment took place in the second and the third trimester.
Results: The adjusted relative risk was increasing by 14% with each day of using antibiotics compared with the reference group (RR = 1.14; 95% CI: 1.01-1.27). When usage of antibiotics was regarded as a dichotomous variable in the logistic model (cut-off point at 5 days), the estimated adjusted risk for persistent wheezing was 4.42 (95% CI: 1.05-18.8). The risk for hay fever due to exposure to antibiotics was 2.65 (95% CI: 1.03-6.81) and a corresponding estimate for eczema was 2.30 (95% CI: 0.91-5.80).
Conclusions: The study suggests that maternal use of antibiotics during pregnancy may prove to be a risk factor for persistent wheezing and development of allergy in early infancy.