Smoking cessation Through Optimisation of clinical care in Pregnancy: the STOP randomised controlled trial

Cigarette smoking negatively impacts on maternal and fetal health. Smoking cessation is one of the few interventions capable of improving pregnancy outcomes. Despite the risks, the most effective antenatal model of care for smokers is still unclear, and specific recommendations for screening for fetal growth restriction are absent.

This is a pragmatic randomised controlled trial of a dedicated smoking cessation clinic versus routine antenatal care as an intervention to reduce cigarette smoking behaviour. Smoking mothers randomised to the Smoking cessation Through Optimisation of clinical care in Pregnancy (STOP) clinic will have all antenatal care provided by a team comprising an obstetrician, a midwife, and a smoking cessation practitioner. This intervention includes ultrasound screening for fetal growth restriction. The control arm comprises two groups: one receiving standard care with ultrasound screening for fetal growth restriction, and one receiving standard care with ultrasound screening for growth restriction only if clinically indicated by their healthcare provider. Four hundred and fifty women will be recruited and randomised to either intervention or control arms stratifying for age, parity, and history of fetal growth restriction.

The primary outcome is self-reported, continuous abstinence from smoking between the quit date and end of pregnancy, validated by exhaled carbon monoxide or urinary cotinine. The quit date is targeted as being at or before 16 weeks' gestation and no further than 28 weeks' gestation. The secondary outcomes are a set of variables including maternal and fetal morbidity and mortality, neonatal complications and delivery outcomes, smoking and psychological outcomes, and qualitative measures.

Despite much research into cigarette smoking in pregnancy, the optimal model of care for these women is still unknown. This study has the potential to improve the model of antenatal care provided to pregnant women who smoke and to improve outcomes for both mother and infant.

ISRCTN11214785 . Registered on 8 February 2018.