City University, London, UK (Ms Bekaert); and St Louis University, St Louis, Missouri (Dr SmithBattle).
Correspondence: Sarah Bekaert, MSc, Child Health Lecturer, City University, London, UK ([email protected]).
We wish to acknowledge Mary M. Krieger, MLIS, RN for her assistance in developing the search strategy.The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article.