A 32-year-old woman presents with primary infertility of 3 years' duration. She has regular menstrual cycles, normal BMI, and no pelvic pain. Her partner has normal semen analysis. Investigations reveal normal FSH, LH, and prolactin levels. Hysterosalpingography shows patent fallopian tubes with normal uterine cavity. Which of the following is NOT a recognized cause of female infertility in this clinical scenario?