BACKGROUND AND AIM: Evidence-based knowledge of how to guide the mothers of preterm infants in breastfeeding establishment is contradictive or sparse. The aim was to investigate the associations between pre-specified clinical practices for facilitating breastfeeding, and exclusive breastfeeding at discharge as well as adequate duration thereof. METHODS: A prospective survey based on questionnaires was conducted with a Danish national cohort, comprised of 1,221 mothers and their 1,488 preterm infants with a gestational age of 24-36 weeks. Adjusted for covariates, the pre-specified clinical practices were analysed by multiple logistic regression analyses. RESULTS: At discharge 68% of the preterm infants were exclusively breastfed and 17% partially. Test-weighing the infant, and minimizing the use of a pacifier, showed a protective effect to exclusive breastfeeding at discharge (OR 0.6 (95% CI 0.4-0.8) and 0.4 (95% CI 0.3-0.6), respectively). The use of nipple shields (OR 2.3 (95% CI 1.6-3.2)) and the initiation of breast milk expression later than 48 hours postpartum (OR 4.9 (95% CI 1.9-12.6)) were associated with failure of exclusive breastfeeding at discharge. The clinical practices associated with an inadequate breastfeeding duration were the initiation of breast milk expression at 12-24 hours (OR 1.6 (95% CI 1.0-2.4)) and 24-48 hours (OR 1.8 (95% CI 1.0-3.1)) vs. before six hours postpartum, and the use of nipple shields (OR 1.4 (95% CI 1.1-1.9)). CONCLUSION: Early initiation of breast milk pumping before 12 hours postpartum may increase breastfeeding rates, and it seems that the use of nipple shields should be restricted. The use of test-weighing and minimizing the use of a pacifier may promote the establishment of exclusive breastfeeding, but more research is needed regarding adequate support to the mother when test-weighing is ceased, as more of these mothers ceased exclusive breastfeeding at an early stage after discharge.