Overall, 22% of the sample endorsed PPD symptoms. In the 2 time-point analysis, controlling for known confounders, participants whose smoking was reduced or unchanged postpartum were about 30% more likely to have PPD compared to those who quit (OR: 1.34; 95% CI = 1.10–1.60, p = 0.001; OR:1.32; 95% CI: 1.10–1.50, p < 0.001 respectively). Participants who increased smoking postpartum were 80% more likely to have PPD compared those who quit (OR: 1.80; 95% CI: 1.50–2.30, p < 0.001). In the 3 time-point analysis, participants who continued smoking at any level during pregnancy and postpartum had 1.48 times the odds of reporting PPD (95% CI: 1.26, 1.73) compared to those who quit during pregnancy and remained quit postpartum. Participants who quit during pregnancy but resumed postpartum had 1.28 times the odds of reporting PPD (95% CI: 1.06, 1.53) compared to those who quit during pregnancy and remained quit postpartum.