Objectives Cigarette smoking during pregnancy is an important modifiable risk factor for poor birth outcomes. We evaluated whether participation in a statewide incentive-based smoking cessation program for pregnant women, the Baby & Me-Tobacco Free (BMTF) program, was associated with improved birth outcomes. Methods Linked program and birth certificate data from 866 pregnant smokers who participated in the BMTF program and 11,568 pregnant smokers who were eligible for but did not enroll in the program were analyzed. The BMTF program consisted of 4 prenatal smoking cessation counselling sessions, 12 postpartum follow-up visits, breath carbon monoxide measurements to monitor smoking status, and rewards of diaper vouchers for quitting smoking. Logistic regression models were used to examine the associations of program participation with infant low birth weight and preterm birth. Results Participants who completed 3-4 prenatal smoking cessation sessions had a significantly lower rate of low birth weight than non-participants (4.9 vs. 11.6 %). After adjustment for multiple potential confounders, the odds ratios for low birth weight were 0.51 (95 % confidence interval, 0.30-0.88) in those participants completing 3-4 sessions and 0.37 (95 % confidence interval, 0.17-0.79) in participants who quit smoking, as compared with non-participants. Although not statistically significant, a protective effect was also suggested for preterm birth. Conclusions We found for the first time that successful participation in the BMTF program, a unique incentive-based smoking cessation program for pregnant women implemented in community settings, was associated with significantly reduced odds of having a low birth weight infant.