Aim To describe reduction as a method in methodological and hermeneutic reduction and the hermeneutic circle using van Manen’s principles, with the empirical example of the lifeworlds of multiple-birth families in Finland.

Background Reduction involves several levels that can be distinguished for their methodological usefulness. Researchers can use reduction in different ways and dimensions for their methodological needs.

Data sources Open interviews with public health nurses, family care workers and parents of twins.

Review methods The systematic literature and knowledge review shows there were no articles on multiple-birth families that used van Manen’s method.

Discussion This paper presents reduction as a method that uses the hermeneutic circle. The lifeworlds of multiple-birth families consist of three core themes: ‘A state of constant vigilance’; ‘Ensuring that they can continue to cope’; and ‘Opportunities to share with other people’.

Conclusion Reduction allows us to perform deep phenomenological-hermeneutic research and understand people’s lifeworlds. It helps to keep research stages separate but also enables a consolidated view. Social care and healthcare professionals have to hear parents’ voices better to comprehensively understand their situation; they also need further tools and training to be able to empower parents of twins.

Implications for research/practice The many variations in adapting reduction mean its use can be very complex and confusing. This paper adds to the discussion of phenomenology, hermeneutic study and reduction.