To Örebro University

Background/objective: Is exposure to maternal infections and use of antibiotics in the prenatal period associated with increased risk of T1D, regardless of genetic risk?

Methods: Data on infections and use of antibiotics during pregnancy were collected from questionnaires at birth from parents to 16 292 children in the All Babies in Southeast Sweden (ABIS) cohort and validated against national diagnosis registers. As of November 2017, 137 ABIS children had developed T1D, 72 boys and 65 girls (0.8% of the original cohort).

Results: More cases were born in spring and summer than fall and winter. However, onset of T1D appeared to be more common in either summer or winter. In univariate analyses, respiratory tract infection in the first trimester (P = .002) and gastroenteritis during pregnancy (P = .04) were associated with later risk of T1D in the offspring. Other types of infection or antibiotic treatment were not associated with an increased risk. In a multiple logistic regression model, a mother with an autoimmune disease (P < .001), father with T1D (P < .001) and respiratory tract infection during the first trimester (P = .005) remained as risk factors for T1D in the offspring. In children with neutral HLA alleles antibiotic treatment may increase the risk of T1D (P = .01, OR 3.46, 95% CI 1.25-9.55).

Conclusions: In the general population there seems to be an association between seasonal maternal respiratory tract infection in the first trimester of pregnancy and later risk of T1D in the offspring. HLA may play a role for the effect of exposure to infections and antibiotics.