Parental bronchial hyperresponsiveness (BHR) and specific IgE, measured before conception and after birth of offspring, as associated with asthma and hayfever in offspring; (A) offspring born in a 10‐year window before and after parental measurement (in ECRHS I); (B) offspring born in a 5‐year window before and after parental measurement (in ECRHS I); and (C) offspring born between parental measurements in ECRHS I (preconception) and ECRHS II (after birth). Here, IGHE is linked to asthma.