@bmj_latest published a large RCT in the UK evaluating the effects of offering pregnant smokers shopping vouchers up to $440 to engage with stop smoking services & stop smoking. Quick take: High-quality RCT finds the offer roughly doubles smoking abstinence in late pregnancy.

Program & Study Design:

  • This multisite study randomly assigned 944 women smokers in early pregnancy, to a treatment group (T) that received the voucher offer + the usual stop smoking services, or a control group (C) that received only the usual stop smoking services.


  • The study found a large, statistically-significant impact on the biochemically-confirmed smoking abstinence rate in late pregnancy: 27% T vs 12% C.

  • Unfortunately, most women relapsed after baby's birth (6 months later, abstinence was 6% T vs 4% C, a difference that wasn’t statistically significant). But abstinence in pregnancy could have benefited the fetus. The study didn't find effects on birth outcomes (e.g., birthweight) but probably needed a larger sample to do so.


  • Based on careful review, I believe this was a high-quality RCT (e.g., with low sample attrition & biochemical confirmation of abstinence). Overall: very encouraging, actionable evidence. Here's the full study report.

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