RESUMEN
The aim of the study was to evaluate the association between in utero exposure to drugs that potentially exhibit immunosuppressive activity and occurrence of infections during the first year of life. We conducted a cohort study on the prescription data of pregnant women and their children registered in EFEMERIS cohort (France), during a one-year period. We classified in utero child exposure according to the number of reimbursements for immunosuppressive drugs during pregnancy. The number of infectious episodes during the first year of life was estimated through the number of anti-infective drugs dispensed. The association was estimated by a quasi-Poisson regression with adjustment for confounders. The study population consisted of 9614 children, 3141 of whom had been exposed to immunosuppressive drugs during pregnancy. The most frequently immunosuppressive drugs prescribed were corticosteroids. The mean number of infectious episodes during the first year after birth gradually increased with the number of immunosuppressive drugs dispensed during pregnancy (from 2.38 in controls to 3.88 in the most exposed group). After adjustment for potential confounders, in utero exposure to immunosuppressive drugs was significantly associated with the number of infectious episodes during the first year of life (RR 3ormoreexposuresVS0=1.35, 95% CI 1.24-1.46). Intrauterine exposure to potentially immunosuppressive drugs could be associated with an increased susceptibility to infections in early childhood.