title: Time-dependent exposures and the fixed-cohort bias.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Barnett
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000633:toxicity*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000187:drug effects*; D050497:Stillbirth / Q000453:epidemiology*
chemical_list: D000393:Air Pollutants