The Basics of Infertility

Infertility is far more common than most people think. According to the American Society of Reproductive Medicine, approximately 6.1 million couples in the United States — about 10 percent of the reproductive-age population — experience fertility problems. For these couples, becoming pregnant is far from easy.

The truth is that hundreds of variables must coincide precisely for conception to occur and for a woman's body to successfully maintain a pregnancy for nine months. The average couple, ages 29 to 33, with no fertility problems, has about a 20 to 25 percent chance of getting pregnant in any given month (or menstrual cycle).


There is no "typical' infertile patient. Ovulation and sperm deficiencies are the most common infertility problems, accounting for two-thirds of all cases.

When ovulation fails to occur, no egg is available for fertilization. The most common symptoms of ovulatory problems are irregular menstrual periods or the absence of menstrual periods.

Less common fertility problems for women include structural problems or scarring of the fallopian tubes and/or uterus caused by pelvic inflammatory disease or endometriosis (a condition causing adhesions and cysts), uterine fibroids or congenital (birth) defects.

Sperm deficiencies can include low sperm production (oligospermia) or lack of sperm (azoospermia). Sperm may also have poor motility — they don't move properly once inside the female reproductive tract to achieve fertilization. Additionally, sperm cells may be malformed or may die before they can reach the egg.

About one-third of infertility cases can be attributed to male factors, and about one-third to factors that affect women. Roughly one-third of infertility is couple-related, with a combination of problems in both partners impeding fertility.

Copyright 2003

National Women's Health Resource Center Inc. (NWHRC).

Likelihood of Infertility

Approximately 5 percent of infertility cases are unexplained; the source of the problem cannot be identified. However, with today's technology, diagnoses of unexplained infertility are declining.

Eighty-five to 90 percent of infertility cases are treated with medication or surgery. In vitro fertilization (IVF) and other types of assisted reproductive technologies (ART) — in which barriers to successful conception are overcome in the laboratory — account for only about 5 percent of infertility treatments.


Ovulation is a complicated balancing act between hormones communicated back and forth between a woman's brain and her ovaries. Ovulation problems occur due to a number of factors:

  • the ovaries may no longer contain fertilizable eggs,
  • ovulation is disrupted because of a breakdown in the hormonal communication cycle
  • scar tissue prevents ovulation from occurring,

And age, indeed, is a major factor in fertility. A 15-year-old girl, for instance, has between a 40 and 50 percent chance per cycle of getting pregnant following intercourse. At age 25, her chances are 30 to 35 percent for pregnancy each month. After age 35, a woman's fertility rapidly declines. By age 43, she has relatively little fertility left because her ovaries now produce fewer viable eggs. Women between ages 40 and 45 have roughly a three percent chance or less per cycle of achieving pregnancy.

The quality of a woman's eggs is critical to her chances of becoming pregnant. Egg quality is particularly important when a couple is considering in vitro fertilization or other ART procedures. These procedures depend on the ovaries responding to stimulation by producing multiple, high-quality eggs. For women older than age 42, physicians may recommend donor egg as an alternative to IVF, for this reason.

While an older woman is more likely to have poorer egg quality than a younger one, the condition can also affect younger women. In women age 30 to 35 who have been diagnosed as infertile, an assessment of their egg quality will show that about 10 percent are so unlikely to get pregnant with their own eggs that the only recourse for pregnancy is donor egg. Poor egg quality is the issue for only about seven percent of women in their 20s who are infertile.

Copyright 2003

National Women's Health Resource Center Inc. (NWHRC).