The Causes of Infertility

DEFINITION OF INFERTILITY — Infertility in a couple is defined as the inability to achieve conception despite one year of frequent unprotected intercourse.

There are many different causes of infertility, and often there are several causes in one couple. These include:

Male factor: In about 25-40 percent of couples, a problem with the sperm is the cause of the infertility. The problem may be the number of sperm, the shape of the sperm, or their ability to move effectively.

Ovulation: In 25-30 percent of couples, there are problems with the production of the woman's egg, or ovulation. This may be the result of an abnormality in the woman's ovary (such as polycystic ovary syndrome), or other hormonal causes. These defects are treated by giving medications to stimulate ovulation.

Tubal defect: Infertility is caused by an abnormality of the Fallopian tubes, the tubes that connect the ovaries to the uterus, in 20-30 percent of couples. Tubal defects can be caused by scarring from previous surgery, infection, or a previous tubal ligation ("tying of the tubes").

Unexplained: There is no obvious cause of infertility in about 10-20 percent of couples. Endometriosis: This is a disorder in which pieces of the lining of the uterus implant themselves onto pelvic organs, including the Fallopian tubes, the ovaries, and sometimes even the intestines. This is the cause of infertility in 5-10 percent of couples.