Smoking cessation Through Optimization of clinical care in Pregnancy: the STOP pragmatic randomized controlled trial

Smoking cessation improves pregnancy outcomes, yet there is uncertainty around the efficacy of models of antenatal intervention for smoking cessation in pregnancy.

This study aimed to test the Smoking cessation Through Optimization of clinical care in Pregnancy (STOP) clinic as an antenatal care pathway for smoking cessation in pregnancy. The STOP intervention is a smoking cessation clinic staffed by a dedicated multidisciplinary team of obstetricians, midwives, and smoking cessation practitioners, who provide motivational and psychological support and intensive clinical monitoring of pregnancy.

This was a pragmatic randomized controlled trial of the STOP clinic compared with routine antenatal care at a tertiary urban maternity hospital delivering >8000 infants per year. The primary outcome measured was continuous abstinence from smoking before 28+0 weeks' gestation, sustained throughout the duration of the pregnancy, and validated using biological measures. The secondary outcomes included maternal and fetal morbidity, delivery and neonatal outcomes, smoking outcomes, and qualitative measures.

A total of 436 women were randomized, with 430 women included in the primary outcome analysis. Women attending the STOP antenatal clinic were more likely to quit smoking compared with those in routine care (odds ratio, 3.62; 95% confidence interval, 1.43-9.17). In addition, women who continued to smoke in the STOP clinic smoked fewer cigarettes daily at the time of delivery compared with controls: 5±4 in the STOP clinic and 7±5 in the control group (odds ratio, 0.28; 95% confidence interval, 0.13-0.59). However, this intervention did not alter postpartum relapse rates (4.3% intervention arm vs 1.5% control arm, not significant) at 4 to 6 months following delivery. The mean birthweight was similar in the intervention and control arms; however, quitters in both groups had infants with significantly higher birthweights compared with those of continued smokers.

The STOP antenatal model of care leads to higher smoking cessation rates among pregnant smokers and lower daily cigarette consumption at time of delivery. Currently, there is no defined or dedicated antenatal pathway for pregnant smokers, despite the high-risk nature of their pregnancies. Our findings suggest that improved smoking cessation rates in pregnancy may be achieved using the holistic approach of the STOP model of care.