Author	I. Tombor
Author	R. West
Author	L. Shahab
Author	J. Brown
Abstract	This thesis reports two strands of work leading to the creation of a smartphone application harnessing identity change to promote smoking cessation during pregnancy. The first strand studied the role of smoker identity in smoking cessation. Using data from a national prospective study of smokers in England, Study 1 found that most young women do not have a positive smoker identity but that those who do are less likely to try to quit smoking, independent of other smoking-related attitudes. Study 2 used prospective national survey data and showed that adopting a non-smoker identity after a quit attempt predicts medium-term abstinence. Study 3 was a meta-ethnography of smoker identity in young adults and found that multiple smoker identities evolve depending on the context and that these do appear to play a role in cessation. The second strand related to the development of the application itself. Using interviews with pregnant smokers, Study 4 found that, from their perspective, stopping smoking would require strong enough motivation, improved ability and a supportive social and physical environment. Study 5 involved focus groups of health professionals working with pregnant smokers and solicited recommendations regarding the design and delivery of digital cessation aids in pregnancy. Study 6 used data from a pilot randomised controlled trial of the smoking cessation website, MumsQuit, to assess associations between exposure to particular components and four-week continuous abstinence. Six behaviour change techniques were associated with abstinence: promoting problem solving, providing feedback on behaviour, promoting self-monitoring of outcomes of the behaviour, providing feedback on outcomes of the behaviour, providing social reward, and promoting self-reward. The thesis concludes with a description of the development of a smartphone application, SmokeFree Baby, based on preceding work.