AbstractAimsTo evaluate whether adding financial incentives to usual care is cost‐effective in encouraging pregnant women to quit tobacco smoking, compared with usual care alone.DesignCost‐effectiveness analysis (CEA) and cost–utility analysis (CUA) from a health‐care provider's perspective, embedded in the Smoking Cessation in Pregnancy Incentives Trial (CPIT III). Long‐term analyses were conducted from the same perspective, using an existing Markov model over a life‐time horizon.SettingSeven maternity smoking cessation sites in Scotland, England and Northern Ireland in the United Kingdom.ParticipantsIn the short‐term analysis, CPIT III participants were assessed: women 16 years or older, self‐reporting as smokers, fewer than 24 weeks pregnant and English‐speaking (n = 944). The same population was used for the life‐time analysis, plus their infants.MeasurementsCosts included financial incentive vouchers and postage, cessation support and nicotine replacement therapy and neonatal stays. The outcome measure was a biochemically verified quit rate for the CEA and quality‐adjusted life‐years (QALYs) for CUA. Costs are presented in 2020 GBP sterling (£). Data for the life‐time analysis came from the trial and were combined with data from published literature embedded in the model, reporting incremental cost per quitter and QALY. A 3.5% discount rate was applied.FindingsThe short‐term incremental cost per quitter was £4400 and cost per QALY was £150 000. Results of sensitivity analyses confirmed these results. The long‐term analysis combined costs and outcomes for mother and infants; results showed a cost saving of £37 [95% confidence interval (CI]) = £35–106] and increase in QALYs of 0.171 (95% CI = 0.124–0.229). These findings indicate that, over a life‐time, financial incentives are cost‐saving and improve health outcomes.ConclusionsIn the United Kingdom, offering up to £400 financial incentives, in addition to usual care, to support pregnant women to stop smoking appears to be highly cost‐effective over a life‐time for mother and infants.