Eligible studies were those that investigated the association between the introduction of a smoking ban in workplaces, public places or both, and one or more specified health outcome, in children. The focus was on children aged 12 years or younger. The primary outcomes were preterm birth, low birthweight, and hospital attendance for asthma. Randomised controlled trials, non-randomised controlled trials, controlled before-and-after studies, and interrupted time series were eligible.
The included studies investigated the effects of district-wide or state-wide bans, in the USA or Canada, or national bans in European countries. Two studies were conducted in Scotland and one in England. The studies investigated neonates or children aged up to 14 years (19 years in one study). The outcomes were from routinely collected data.
Final study selection was based on consensus between two reviewers, with arbitration by a third reviewer if necessary.