Objective: To examine whether an efficacious voucher-based incentives intervention for decreasing smoking during pregnancy and increasing fetal growth could be improved without increasing costs. The strategy was to redistribute the usual incentives so that higher values were available early in the quit attempt.
Method: 118 pregnant smokers in greater Burlington, Vermont (studied December, 2006-June, 2012) were randomly assigned to the revised contingent voucher (RCV) or usual contingent voucher (CV) schedule of abstinence-contingent vouchers, or to a non-contingent voucher (NCV) control condition wherein vouchers were provided independent of smoking status. Smoking status was biochemically verified; serial sonographic estimates of fetal growth were obtained at gestational weeks 30-34.
Results: RCV and CV conditions increased point-prevalence abstinence above NCV levels at early (RCV: 40%, CV: 46%, NCV: 13%, p=.007) and late-pregnancy (RCV: 45%; CV: 36%; NCV, 18%; p=.04) assessments, but abstinence levels did not differ between the RCV and CV conditions. The RCV intervention did not increase fetal growth above control levels while the CV condition did so (p<.05).
Conclusion: This trial further supports the efficacy of CV for increasing antepartum abstinence and fetal growth, but other strategies (e.g., increasing overall incentive values) will be necessary to improve outcomes further.
Trial registration: ClinicalTrials.gov NCT01801384.
Keywords: Birth outcomes; Contingency management; Fetal growth; Financial incentives; Pregnancy; Smoking cessation; Tobacco; Vouchers.
Copyright © 2014 Elsevier Inc. All rights reserved.