Aim: To establish the relationships between age, mode of conception and breastfeeding. Method: Consecutive cohorts of nulliparous women >25 weeks pregnant who had conceived through ART (ARTC) or spontaneously (SC) in three age groups ≤30, 31-36 and ≥37 years were recruited. Data were obtained via telephone interviews and postal questionnaires in late pregnancy and 4 months postpartum. Sociodemographic characteristics, reproductive health, birth and breastfeeding experiences were assessed by study-specific questions. Self-rated general health and symptoms of depression and anxiety were assessed with standardized psychometric instruments. Main outcomes were exclusive breastfeeding at discharge from maternity hospital and 4 months postpartum. Results: Of 1179 eligible women, 791 (67%) participated; 549 (93%) had singleton infants, provided complete data and were included in analyses. Overall, 37.2% of participants aged ≤30, 33% aged 31-36 and 55.1% aged ≥37 years experienced Caesarean births. Regardless of age, compared with the SC group, ARTC women had twice the rate of Caesareans prior to labour. Controlling for other factors, exclusive breastfeeding rates at hospital discharge and 4 months postpartum were lowest amongst ARTC women who experienced Caesarean prior to labour (p <.001). Conclusion: Independent of age, assisted conception increases the risk conferred by Caesarean birth to breastfeeding initiation and maintenance.