Modern midwifery practice should be based on the findings of up-to-date research, which is necessarily changing and dynamic. The Midwifery Practice Series was specifically designed to enable busy practitioners and students to have access to a broad-ranging survey and analysis of the literature in a form that draws out the research-based implications for practice. With the `Core Topics' books the Midwifery Practice series is relaunched and updated. The latest research findings and the implications for midwifery care in the wake of the 'Changing Childbirth' report are considered, along with seminal earlier work. The relationship between critically reviewed research findings and good practice remains essential.