Preschool wheezing and related hospitalization rates are increasing. Prenatal tobacco smoke exposure (PTSE) increases the risk of wheezing, yet >20% of French women smoke during pregnancy. In this observational retrospective monocentric study, we assessed the link between PTSE and hospital admissions. We included infants <2 years of age admitted for acute wheezing. A phone interview with mothers was completed by electronic records. The primary endpoint was the ratio of cumulative duration of the hospitalization stays (days)/age (months). 129 children were included (36.4% exposed to PTSE vs. 63.6% unexposed). There was a significant difference in the duration of hospitalization/age: 0.9 days/month (exposed) vs. 0.58 days/month (unexposed) (p = 0.008). Smoking one cigarette/day during pregnancy was associated with an increase in hospitalization duration of 0.055 days/month (r = 0.238, p = 0.006). In the multi-variable analysis, this positive association persisted (β = 0.04, p = 0.04; standardized β = 0.27, p = 0.03). There was a trend towards a dose-effect relationship between PTSE and other important parameters associated with hospital admissions. We have demonstrated a dose-effect relationship, without a threshold effect, between PTSE and duration of hospitalization for wheezing in non-premature infants during the first 2 years of life. Prevention campaigns for future mothers should be enforced.
Keywords: adverse effect; asthma; child; delayed effects; pregnancy; prenatal exposure; preschool; smoking.