ABSTRACTAims This study examined whether voucher‐based reinforcement therapy (VBRT) contingent upon smoking abstinence during pregnancy is an effective method for decreasing maternal smoking during pregnancy and improving fetal growth.
Design, setting and participants A two‐condition, parallel‐groups, randomized controlled trial was conducted in a university‐based research clinic. A total of 82 smokers entering prenatal care participated in the trial.
Intervention Participants were assigned randomly to either contingent or non‐contingent voucher conditions. Vouchers exchangeable for retail items were available during pregnancy and for 12 weeks postpartum. In the contingent condition, vouchers were earned for biochemically verified smoking abstinence; in the non‐contingent condition, vouchers were earned independent of smoking status.
Measurements Smoking outcomes were evaluated using urine‐toxicology testing and self‐report. Fetal growth outcomes were evaluated using serial ultrasound examinations performed during the third trimester.
Findings Contingent vouchers significantly increased point‐prevalence abstinence at the end‐of‐pregnancy (41% versus 10%) and at the 12‐week postpartum assessment (24% versus 3%). Serial ultrasound examinations indicated significantly greater growth in terms of estimated fetal weight, femur length and abdominal circumference in the contingent compared to the non‐contingent conditions.
Conclusions These results provide further evidence that VBRT has a substantive contribution to make to efforts to decrease maternal smoking during pregnancy and provide new evidence of positive effects on fetal health.
