Association between the timing of asthma diagnosis and medication use during pregnancy

Abstract

Asthma medication use during pregnancy is recommended by international guidelines to maintain control of symptoms since poor control has been shown to increase the risk of adverse perinatal outcomes. To date, no studies have evaluated the association between the timing of new-onset asthma and the use of asthma medications during pregnancy. The objective of this study is to assess whether asthma medication use during pregnancy differs in women with asthma diagnosed during the first 19 weeks of pregnancy compared to those diagnosed 2 years before pregnancy. We conducted a retrospective cohort study using the Quebec asthma and pregnancy database. The primary outcome was the use of inhaled corticosteroids (ICS), ICS/long-acting ß2agonists (LABA) and short-acting ß2-agonists (SABA) during pregnancy defined as the number of filled prescriptions from 20 weeks of pregnancy (Cohort entry-CE-) until delivery. Oral corticosteroids (OCS) use during pregnancy was defined as the number of days of filled prescriptions from CE until delivery. Poisson regression models were used to compare the rates of asthma medication use between women diagnosed before and early in pregnancy, while adjusting for potential confounders. The secondary outcomes were the treatment dispensed at diagnosis defined as asthma medications filled at the pharmacy in the month prior and the month following the date of asthma diagnosis and adherence to ICS during follow-up estimated with the proportion of days covered (PDC). The cohort included 1 731 women with asthma diagnosed before and 359 early in pregnancy.