Infertility In Women - Introduction

Introduction

Infertility is the failure of a couple to become pregnant after one year of regular, unprotected intercourse. In both men and women the fertility process is complex.

Infertility affects about 10% of all couples. Even under ideal circumstances, the probability that a woman will get pregnant during a single menstrual cycle is only about 30%. When conception does occur, only 50 - 60% of pregnancies advance beyond the 20th week. (The inability of a woman to produce a live birth because of abnormalities that cause miscarriages is called infecundity and is not discussed in detail in this report.)

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About a third of infertility problems are due to female infertility, and another third are due to male infertility. In the remaining cases, infertility affects both partners or the cause is unclear. Although this report specifically addresses infertility in women, it is equally important for the male partner to be tested at the same time. [For more information, see In-Depth Report #67: Infertility in men.]

The Female Reproductive System

The primary organs and structures in the reproductive system are:

• The uterus is a pear-shaped organ located between the bladder and lower intestine. It consists of two parts, the body and the cervix.
• When a woman is not pregnant the body of the uterus is about the size of a fist, with its walls collapsed and flattened against each other. During pregnancy the walls of the uterus are pushed apart as the fetus grows.
• The cervix is the lower portion of the uterus. It has a canal opening into the vagina with an opening called the os, which allows menstrual blood to flow out of the uterus into the vagina.
• Leading off each side of the body of the uterus are two tubes known as the fallopian tubes. Near the end of each tube is an ovary.
• Ovaries are egg-producing organs that hold 200,000 - 400,000 follicles (from folliculus, meaning "sack" in Latin). These cellular sacks contain the materials needed to produce ripened eggs, or ova.
• The inner lining of the uterus is called the endometrium. During pregnancy, it thickens and becomes enriched with blood vessels to house and support the growing fetus. If pregnancy does not occur, the endometrium is shed as part of the menstrual flow. Menstrual flow also consists of blood and mucus from the cervix and vagina.