Implantation Problems – This is a significant cause of fertility problems and cannot be adequately assessed diagnostically.  An endometrial biopsy can be performed, but is uncommon.  Ultrasound can measure endometrial thickness, but not receptivity.  Excess estrogen impairs implantation and progesterone increases receptivity of the uterine lining to implantation.

Stress – This is also a significant factor in unexplained infertility and can be difficult for the patient to overcome. Adrenal gland hyperstimulation leads to excessive cortisol production, depleting crucial progesterone stores. Failure to conceive in and of itself can be a stressor for the patient so that tensions escalate the longer the infertility lasts, perpetuating the fertility issues.

Poor timing – Many patients are not properly educated as to how to determine when ovulation occurs and when to time intercourse. 

Hostile vaginal environment – What is often referred to as a hostile vaginal environment is more often a lack of or poor quality cervical mucous.  Cervical mucous acts as the gatekeeper to the uterus, at ovulation its consistency changes and becomes more conducive to transport of sperm into the uterus. 

Undiagnosed PCOS – A diagnosis of Polycystic Ovarian Syndrome does not require multiple cysts to be visualized on ultrasound.  Many women will have a cluster of symptoms of PCOS without actually have cysts on the ovaries.  Look for hirsutism, irregular menstruation, acne (chest, back, face), difficulty losing weight or easily gain weight, symptoms of hypoglycemia, insulin resistance or high fasting insulin levels, and elevated DHEAs.

Excess xenoestrogens - Xenoestrogens from pollution, herbicides, pesticides, plastics, conventional meat and dairy products and contraceptives can block estrogen receptors interfering with normal estrogen function.  Estradiol levels may be normal, but estrogen function may be affected.