Table 1

Intervention and research participation incentives

Time pointInterventionControl
Initial local smoking cessation services meeting and setting quit date£50 voucherN/A
Verified quit at 4 weeks after quit date£50 voucherN/A
Verified quit at 12 weeks after quit date£100 voucherN/A
Verified quit at 34–38 weeks gestation and provision of urine/saliva sample if quit£200 voucherN/A
Providing data for primary outcome£50 voucher for research participation£50 voucher for research participation
Providing data for secondary outcome (quit 6 month postpartum)£25 voucher for research participation£25 voucher for research participation