Abstract Objective the aim of this study was to assess the impact of providing intensified support for breast feeding during the perinatal period. Design a quasi-experimental design with non-equivalent control group. Setting three public maternity hospitals (two study, one control) in the Helsinki Metropolitan area in Finland. Participants a convenience sample of 705 mothers (431 in the intervention group, 274 in the control group). Methods and intervention in this study, families in the intervention group had access to intensified breast feeding support from midpregnancy, whereas those in the control group had access to normal care. Intensified support included lectures and workshops to health professionals, and families in the intervention group had access to more intensive support and counselling for breast feeding and a breast feeding outpatient clinic. Additionally, an internet-based intervention was only used in the intervention group, but not in the control group. Mothers in the control group received normal care from the midwifery and nursing professionals who were to continue their work normally. The data were analysed statistically. Findings altogether 705 women participated in the study. In the intervention group (n=431), 76% of the women breast fed exclusively throughout the hospital stay, compared to 66% of the mothers in the control group (n=274). In multivariate analysis, the likelihood of exclusive breast feeding at the time of responding (at hospital discharge or after that at home) was increased by the mother not being treated for an underlying illness or medical problem during pregnancy, being in the intervention group, having normal vaginal childbirth, high breast feeding confidence, positive attitude towards breast feeding, good coping with breast feeding, and 24-hour presence of the infant's father in the ward. Key conclusions and implications for practice the low exclusive breast feeding rates of newborns could be increased by using intensified breast feeding support. Mothers' health problems during pregnancy can decrease exclusive breast feeding. Mothers with health problems or other than normal childbirth should receive extra breast feeding support, and the presence of fathers in the ward should be encouraged. Intensified breast feeding counselling and support helps mothers to breast feed exclusively. This support should be available in a variety of forms, so that mothers can choose the type of support they need. As breast feeding counselling and support is intensified, more mothers succeed with exclusive breast feeding.