Objective To examine the association between low-intensity smoking (10 or less cigarettes per day) and all-cause and cause-specific mortality risk among women who smoke and by age at cessation among women who previously smoked.

Methods In this study, 104 717 female participants of the Mexican Teachers’ Cohort Study were categorised according to self-reported smoking status at baseline (2006/2008) and were followed for mortality through 2019. We estimated HRs and 95% CIs for all-cause and cause-specific mortality using multivariable Cox proportional hazards regression models with age as the underlying time metric.

Results Smoking as few as one to two cigarettes per day was associated with higher mortality risk for all causes (HR: 1.36; 95% CI 1.10 to 1.67) and all cancers (HR: 1.46; 95% CI 1.05 to 2.02), compared with never smoking. Similarly, slightly higher HRs were observed among participants smoking ≥3 cigarettes per day (all causes HR: 1.43; 95% CI 1.19 to 1.70; all cancers HR: 1.48; 95% CI 1.10 to 1.97; cardiovascular disease HR: 1.58; 95% CI 1.09 to 2.28).

Conclusions In this large study of Mexican women, low-intensity smoking was associated with higher mortality risk for all causes and all cancers. Interventions are needed to promote cessation among women who smoke at low-intensity in Mexico, regardless of how few cigarettes they smoke per day.