There are several potential causes of infertility in the female and in the male. Given the high incidence of male infertility, a complete evaluation of the male should always be performed. This is true even if a fertility problem has already been identified in the female. Very often there is a combination of female and male infertility factors.

Causes of Infertility

The processes listed below must occur in order for a pregnancy to result.

1. The male must produce healthy sperm that can reach and fertilize an egg.
2. Tubal disease- the tubes must be open and free of obstructions that can be caused by endometriosis, scarring, infection, and other conditions. The eggs travel through the tubes from the ovaries to the uterus.
3. Ovulatory disease- healthy follicles must be recruited and mature eggs must be ovulated. These processes are controlled by hormonal interactions between the hypothalamus gland and the pituitary gland. FSH stimulates follicular development and a surge of luteinizing hormone (LH) stimulates ovulation.
4. Cervical disease- the cervical mucus must support and nourish the sperm and it must be free of antisperm antibodies.
5. Endometriosis- endometriosis can attach to, and penetrate, the reproductive organs including the tubes. It can cause blockage and other damage to these organs.
6. Uterine factor infertility - the uterus must be free of large obstructions such as polyps and fibroids.
7. The endometrium must thicken and develop to accept a developing embryo. Sometimes the endometrium does not develop appropriately and this is known as a “luteal phase” defect. The fertilized egg (embryo) must travel to, and implant in, the endometrium.
8. Female age / ovarian factor and infertility - as women age, their eggs loose the capacity to fertilize and develop.
9. The egg and sperm must combine to form a healthy embryo with a normal number of chromosomes.
10. The female must be healthy and capable of carrying a baby to term.
    

Abnormal processes, or diseases, effecting any one, or a combination, of these steps can lead to infertility. Typically, common causes include: 1) irregular or failed ovulation 2) hormonal imbalances
3) damaged or blocked fallopian tubes 3) poor cervical mucus 4) a deformed uterus or the presence of large polyps and/or fibroids. 5) genetic disease 6) immunological 7) significant endometriosis which can negatively effect many processes. 8) inadequate sperm ( poor quantity or quality) . Also, once the fetus begins development, the mother must be able to carry the baby to term. Spontaneous abortion is a major cause of infertility, which can have many causes but most often results from embryonic genetic abnormalities (i.e. wrong number of chromosomes).

We discuss all of these potential infertility causes on this, and other Web pages.

Unexplained Infertility

One of the most frustrating diagnosis a couple can receive is unexplained infertility. It is our “nature” to seek the cause(s) of any medical condition negatively affecting our body.

“Unexplained” does not mean there is no cause of a couple’s infertility. Essentially, science and reproductive medicine have not advanced to the point where the cause can be identified.  As more research is done, the numerous “undiscovered” causes of infertility will be delineated. An example is the advances made in male infertility. Many couples who had “mild male factor infertility” would probably have been diagnosed as “unexplained” several years ago.  We have gotten much better in identifying the many aspects of sperm “quality”.

Most experts believe that a large segment of “unexplained infertility” is due to genetic disease in either the sperm or egg.  Their may be problems with fertilization and embryonic development that have not been characterized by scientists.  In fact, many couples with unexplained infertility opt for IVF because the fertilization of the egg by the sperm can be observed and documented by the embryologist.

Luteal Phase Defect

Once successful fertilization occurs, the embryo travels to, and implants in, the lining of the uterus, known as the endometrium.  During embryonic and fetal growth the endometrium provides nourishment.

The lining of the uterus must thicken and become much more vascular to provide the needed nutrients.   Endometrial cells are “fast growing” and develop rapidly under the influence of estrogen and progesterone. Endometrial cells ability to rapidly grow and divide is the cause of endometriosis wherein the cells attach to, and sometimes penetrate, organs and other structures.

Too little progesterone can lead to a “luteal phase defect” wherein the endometrium does not develop properly. This defect is usually corrected by the administration of progesterone during the ovulatory cycle.