Table 1

Prevalence of childhood environmental factors (%) by country in subjects born between 1945 and 1970

IcelandNorwaySwedenEstoniaIrelandUKNethBelgiumGermanySwitzFranceSpainItalyNZAustrUSATotal
*“Did you regularly share your bedroom with any older children before the age of five years?”
†“Did you go to a school, play school, or nursery with any older children before the age of five years?”
‡“Did you have a serious respiratory infection before the age of five years?”
n5648351856431454157912471122198385321251943894125466872318530
No of siblings
    09511213851119121341456610
    1122536477322625393330243920282129
    22635262112292523202624262526272625
    3202014615141615111415191119162115
    ≥4321513562172826111519271230232621
Bedroom sharing*5149444370373939444741484942484244
Day care attendance†2830204551397987522857556053633049
Serious respiratory infection‡111211151097101011661012141010