Sometimes even after all fertility testing has been exhausted no cause for a couple’s infertility can be found. This does not mean there is no cause, only that it cannot be identified. This is perhaps the most difficult “diagnosis”.

IVF is sometimes an option for couples with unexplained infertility. IVF provides information about fertilization and embryo development that cannot be gained by other means. The embryologist can visualize and document fertilization and follow embryonic development for the first days.

Many authorities postulate genetic causes for unexplained infertility that relate to fertilization and embryonic growth. Sometimes preimplantation genetic diagnosis (PGD) can be used to rule out aneuploidies (abnormal number of chromosomes) or identify specific genetic diseases. As women age, their egg quality declines in some ways that have not yet been defined. These changes may be responsible for a significant number of unexplained infertility cases. Many of these women solve the dilemma of unexplained infertility by using donor eggs.

Subtle sperm abnormalities may also contribute to unexplained infertility. Sperm production, transport, delivery to the uterus, egg penetration, and fertilization are complex processes. There could be any number of biochemical reactions/requirements affecting these processes that have not yet been identified.

As time progresses, new and exciting discoveries are made in the infertility arena. When knowledge of infertility’s causes increases, we can expect a decline in the number of cases of unexplained infertility.