Introduction: Diastasis recti abdominis (DRA) is both a structural and a functional disorder. It is believed that the main cause of DRA is the extensive stretching of the abdominal wall resulting from pregnancy; yet the condition is also found in men and in children. There are several, seemingly mutually exclusive, DRA risk factors, such as the pathological abdominal muscle tension and chronic exercise deficits. The aim of the study was to determine the factors affecting the size of DRA in postpartum women. Material and methods: The study involved 239 postpartum women. The study was conducted with the use of an online survey. The subjects completed the DRA test, the Beighton test and International Physical Activity Questionnaire. Results: The analysis found DRA in majority of studied women (60.7%). The relationship between the BMI index and DRA was statistically significant (p=0.01). The relationship between surgeries in the abdominal cavity and the DRA was statistically significant, too (p=0.05). We showed that DRA correlates with other pelvic dysfunctions (p=0.03). Conclusions: The most significant risk factors for diastasis recti abdominis in postpartum women are abnormal BMI and surgeries to the abdominal cavity. Diastasis recti abdominis correlates with other dysfunctions, such as: spinal pain, urinary incontinence, peristaltic disorders, sexual disorders, abdominal hernia, groin hernia, lowering of the lesser pelvis organs. Further studies into DRA risk factors under close supervision of a physiotherapist are necessary.