[1] Univ Sussex, Sch Psychol, Brighton, E Sussex, England
[2] Brighton & Sussex Univ Hosp Trust, Royal Alexandra Childrens Hosp, Acad Dept Paediat, Brighton, E Sussex, England
[3] Bliss, London, England
[4] Natl Childbirth Trust, London, England
[5] Univ Nottingham, Nottingham Clin Trials Unit, Nottingham NG7 2RD, England
[6] City Univ London, Sch Hlth Sci, London EC1V 0HB, England