Several factors can make it difficult or impossible for a woman to become pregnant. But treatment does help in some cases, even if the cause can't be found.
Nationwide, about 6.7 million women and their partners face infertility. Infertility problems can be attributed to female factors in roughly one-third of these cases, to male factors in another one-third, and to a combination or to unknown factors in the remaining one-third.
Common reasons for infertility in women include problems with:
- The ovaries
Irregular ovulation (egg production) accounts for 25% of all infertility cases, according to the American Society for Reproductive Medicine (ASRM). In some cases the ovaries don't produce eggs at all.
The ovaries also produce the hormone that signals the uterus to prepare for an egg. Low production may prevent pregnancy.
- The fallopian tubes
Blocked, scarred or damaged fallopian tubes prevent sperm from reaching the egg for fertilization. This damage often results from disease.
Surgery may repair the fallopian tubes. Severe damage makes pregnancy very unlikely, and in vitro fertilization may be recommended.
- The cervix
Sperm need to travel through the cervix to reach the egg. If the cervical mucus is too thick, the sperm can't get through. The presence of certain proteins in the cervix can kill or immobilize the sperm.
Treatment for cervical problems includes antibiotics and hormonal therapy. A fertilized egg may also be inserted directly into the uterus.
- The uterus
Scar tissue, polyps, fibroids or a misshapen uterus can prevent pregnancy. These factors may prevent the egg from attaching to the uterine wall or cause miscarriage.
- The abdominal cavity
Scar tissue on the outside surfaces of reproductive organs may interfere with fertility. Endometriosis, a condition where tissue that usually lines the inside of the uterus starts to grow on the outside, also hampers fertility. This tissue can grow on any organ in the abdominal cavity.
Subtler and less common causes are harder to diagnose.
Common infertility treatments include surgery and medication. They can work even when the cause of infertility can't be found.