Infertility- Common Causes

There are several complex processes that must occur in order for you to become pregnant and carry a baby to term. Disruption of any of these processes can lead to infertility. In the simplest terms, these reproductive processes are as follows (We discuss each process in detail in separate Web site sections):

1. The normal menstrual cycle is governed by a series of complex hormonal interactions. These hormones include estrogen, follicle stimulating hormone (FSH), leutinizing hormone (LH), progesterone, human chorionic gonadotropin, and others. Your ovaries must be capable of producing follicles, containing eggs, under the influence of FSH. These eggs must develop to maturity and ovulate after a surge of LH. Irregular ovulation (oligoovulation) and lack of ovulation (anovulation) are major causes of infertility. Your eggs must also be genetically “healthy” and capable of being fertilized.
2. Your reproductive organs must be free of obstructive endometriosis. Endometriosis can also create an inflammatory environment in your pelvic cavity, which could adversely impact fertilization.
3. You must be free of major pelvic infections (PID) such as Chlamydia.
4. Your partner must produce an adequate quantity of “good quality” sperm and ejaculate them into your vagina. The semen analyses examine several characteristics such as count, mobility (swimming), shape, motility, viscosity, and others. The male’s testicles must be capable of producing “sperm” which can travel through the vas deferens (tube carrying semen) and be ejaculated. The sperm must be free of genetic abnormalities.
5. Sperm must travel through the vagina into the uterus to the end of the fallopian tube, where fertilization occurs. Cervical factor infertility occurs when your mucus is “too thick” or there is scarring of the cervix from past surgery such as cone biopsy.
6. Once the sperm reach the egg, one sperm must attach to the zona pellucida (membrane surrounding the egg), penetrate it, and deposit its genetic material.
7. Once successful fertilization occurs, the resultant embryo travels to, and implants in, the lining of the uterus (endometrium). The endometrium must be thick and vascular to accept and support the developing embryo. This occurs under the influence of estrogen and progesterone during the menstrual cycle.
8. Your uterus must be normally shaped and free of large obstructions such as fibroids or polyps.
9. After the embryo attaches to the uterus, the ruptured follicle remaining on the ovary must begin to produce progesterone. This structure is known as the corpus luteum.
10. As the embryo grows, the placenta also begins to produce progesterone to support the pregnancy.
11. You must be healthy and capable of carrying the baby to term and delivery.

Based upon these processes the causes of infertility are typically divided into the following categories: