The trial aims to determine whether or not MiQuit (text-message support programme) is effective when offered in addition to standard behavioural support for smoking cessation in pregnancy.

Smoking in pregnancy is expensive; in the UK in 2010 the annual smoking-attributable maternal and infant health care costs were estimated at up to £87.5 million. In high income countries 13% to 25% of pregnant women smoke and rates are increasing in developing ones. In the UK in 2010 26% of pregnant women smoked with highest rates seen amongst younger, socially disadvantaged women.

However, pregnancy is the life event which most motivates smoking cessation attempts and 50+% of pregnant smokers try stopping, hence smoking cessation support offered in pregnancy is likely to be especially beneficial. Regrettably, in pregnancy, there is only strong efficacy evidence for using either face-to-face or 'self-help' stop smoking support. Although nicotine replacement therapy (NRT) is widely-used by UK pregnant smokers this has at best, borderline efficacy.

Self-help support (SHS) almost doubles the likelihood of smoking cessation in late pregnancy. However SHS programmes which help pregnant smokers to quit were all developed before easily-accessible technologies became widely available.

Text message SHS smoking cessation programmes are highly-acceptable; those trialled with non-pregnant smokers in the US and UK have demonstrated efficacy. Unfortunately, neither programme is appropriate in pregnancy as they make no mention of pregnancy which for most pregnant smokers is the very reason they try quitting; consequently many pregnant smokers would likely find these programmes' advice irrelevant and ignore it.

Funded by CRUK to remedy the lack of acceptable self-help cessation support for pregnant smokers, we developed MiQuit, a text-message, smoking cessation SHS programme for pregnant smokers. MiQuit advice is relevant to pregnancy as it is highly-tailored to gestation. We evaluated MiQuit in two RCTs. The first CRUK-funded trial (n=207) demonstrated acceptability. Subsequently, with NIHR funding we refined MiQuit and tested this in a second RCT which demonstrated the feasibility of recruiting from UK National Health Service (NHS) settings to a multi-centre RCT. Again estimated efficacy was encouraging; in MiQuit and control groups, prolonged abstinence from smoking, validated in late pregnancy was 5.4% and 2.0% respectively.

To efficiently determine whether or not MiQuit works for smoking cessation, we are conducting a third RCT with an almost identical design. The efficacy of the MiQuit system will be assessed by combining the findings, using Trial Sequential Analysis methods, from this trial with the findings from the previous two MiQuit trials. Without requiring an expensive, large RCT this study will tell whether or not MiQuit is efficacious for smoking cessation in pregnancy.

Inclusion Criteria:

• Pregnant and less than 25 weeks gestation
• Smoking at least 5 cigarettes per day pre-pregnancy
• Smoking at least 1 cigarette on a typical day during pregnancy
• Aged 16 or over
• Agrees to accept information to assist cessation
• Owns or has primary use of a mobile phone
• Familiar with sending and receiving text messages
• Able to understand written English (text messages are in English only) and consent issues explained in English.
• Able to give informed consent

Exclusion Criteria:

• Already enrolled in another text service to assist smoking cessation
• Already enrolled in a smoking cessation study
• Having already participated in the study in an earlier pregnancy