OBJECTIVE: To examine the effects of cesarean and forceps or vacuum delivery and parental smoking habits on the initiation and duration of breast-feeding. METHODS: We conducted a prospective, population-based birth cohort study in 1997. Data were collected on breast-feeding history, household smoking habits, method of delivery, and other demographic, obstetric, behavioral, and potential confounding variables via a standardized self-administered questionnaire. Multivariable logistic regression was used to examine the association between method of birth (cesarean versus forceps or vacuum delivery versus normal vaginal birth) and either not initiating breast-feeding or doing so for less than 1 month. Among women who breast-fed for 1 month or more, multivariable survival analysis was employed to study the relationship between method of delivery and breast-feeding duration. We repeated these analyses to examine the link between parental smoking habits and breast-feeding initiation and duration. RESULTS: A total of 7825 mother-infant pairs were followed up for 9 months. Cesarean delivery was a risk factor for not initiating breast-feeding, for breast-feeding less than 1 month, and remained a significant hazard against breast-feeding duration. Assisted delivery with forceps or vacuum, although not associated with breast-feeding initiation, was a significant risk against breast-feeding duration. Conversely, current parental smoking habits only affected breast-feeding initiation but were unrelated to breast-feeding duration. CONCLUSION: This study indicates a possible effect of forceps or vacuum delivery on breast-feeding and of cesarean on long-term breast-feeding duration. The findings provide additional evidence in support of the avoidance of unnecessary obstetric interventions.