Characteristics of included studies: cohort studies.

a<p>Please see <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1001596#pmed.1001596.s018" target="_blank">Table S2</a> for detailed assessment.</p>b<p>≥3 patient encounters ≥14 d apart, with a diagnosis of asthma or wheezing; and/or ≥1 such encounter with a prescription for oral corticosteroids between 2 d before and 7 d after the encounter; and/or ≥1 hospitalisations for ≥24 h or until death occurred, with a diagnosis of asthma or wheezing; and/or ≥4 dispensing events ≥14 d apart, for which selected asthma medications were prescribed plus ≥1 encounters with a diagnosis of asthma or wheezing; and/or death outside the hospital due to asthma or wheezing.</p><p>ATC, Anatomical Therapeutic Chemical Classification System; GA, gestational age; ICD, International Classification of Diseases; KPNC, Kaiser Permanente Northern California; KPSC, Kaiser Permanente Southern California; LMP, last menstrual period; PC, prospective cohort; RC, retrospective cohort.