The frequency of occurrence of FN-fibrin complexes was as follows: For 1000 kDa—0.61 and 0.75, for 1300 kDa—0.55 and 0.64 and for 1600 kDa—0.45 and 0.42, for the groups of endometriosis and fertility disorders, respectively. Here, FN1 is linked to infertility disorder.