Background: The purpose of the research was to determine the prevalence and location of diastasis recti abdominis muscle (DRA) during pregnancy and puerperium in women in the Ljubljana maternity hospital. Methods: The study sample included sixty randomly selected women; forty-five pregnant and postpartum women were recruited from the Ljubljana Maternity Hospital, and fifteen non-pregnant women from the larger Ljubljana area as a control group. All women were examined for the presence or absence of diastasis recti abdominis muscle along with the most and least likely location along the white lines. The measurements were performed by the finger-width method. Results: The findings indicate that the diastasis recti abdominis muscle increases with the progression of pregnancy. In the case of non-pregnant women, the diastasis is not present. The presence of DRA was first observed in the second trimester of pregnancy (9.5 %) and was most common in the third trimester (52.4 %). After birth, the incidence decreased (38.1 %). The majority of diastasis recti abdominis cases were observed in the umbilical area (52.6 %) in the third trimester. In the puerperium group three days after childbirth the diastasis below the umbilicus was most common (60.0 %) and slightly less common above the umbilicus (53.8 %). Conclusion: Diastasis recti abdominis muscle during pregnancy and after childbirth is a common condition. It is therefore recommended that all women should be timely examined for the presence of DRA before and after birth along the linea alba to start timely and adequate physiotherapy treatment. Health professionals as well as sports teachers and coaches who work with pregnant and puerperium women should be educated/trained in the field of testing and treatment of diastasis recti abdominis muscle.