Infertility is more common than previously thought and occurs in approximately 10 to 15 percent of couples at some time during their reproductive lives.
Infertility is defined as the inability to conceive after one year of unprotected intercourse.
Infertility is a condition that can affect either or both partners so each should be thoroughly evaluated. Male infertility is a factor about 47 percent of the time.
Women over age 35 are advised to start infertility evaluation after 6 months of unprotected intercourse so as not to delay treatment.
The Reproductive Process
A complex series of biologic events must occur for pregnancy to result.
- The ovary must contain eggs that will develop to maturity within the ovarian follicles under the influence of follicle stimulating hormone (FSH).
- The egg must be released (ovulated) from the follicle and travel through an open fallopian tube to the end near the uterus where fertilization occurs.
- The male must produce enough sperm to cause fertilization. A significant number of these sperm must be “normal” as determined by their shape, swimming ability, and several other characteristics.
- The sperm must travel through the vas deferens and urethra and be ejaculated into the vagina.
- Once deposited, the sperm must swim through the cervical mucus into the uterus.
- Once the sperm reaches the egg it must attach to and penetrate the outer membrane (zona pellucida). The DNA of the male and female must combine to produce a full complement of chromosomes.
- After the egg is fertilized, it divides to become an embryo. The embryo must travel into the uterus where it implants in the endometrial lining.
- Once the embryo implants, its nourishment and development are supported by progesterone and other hormones.
- The uterus must be capable of supporting the growing fetus.
Infertility Causes
When one or more of the steps in the reproductive process are impaired, infertility can result. Most cases of female infertility are due to medical conditions that cause these impairments.
Ovulation is the release of the egg that occurs during the monthly menstrual cycle. Problems that affect ovulation, and the hormones involved in ovulation, are the most common cause of female infertility.
Ovulation may occur irregularly (oligoovulation) or not at all (anovulation).
Anovulation can be caused by numerous factors including stress, pituitary disorders, obesity, anorexia, polycystic ovarian disease, disorders of the adrenal or thyroid glands, elevated levels of prolactin (hyperprolactinemia), and others.
As a woman approaches menopause, her eggs lose their capacity to develop and fertilize. The period preceding menopause is called perimenopause and is evidenced by irregular ovulation.
There are other complex causes of ovulatory dysfunction and ovarian failure. A reproductive endocrinologist should be consulted early in the evaluation so a specific cause can be identified and the best treatment initiated.
A blocked fallopian tube can prevent sperm from reaching and fertilizing the egg. Blockage in the fallopian tube can also prevent a fertilized egg from traveling to the uterus for implantation.
The fallopian tubes can become blocked as a result of endometriosis, adhesions, infection, scarring from previous surgery, congenital defects, or they may have been “tied” for birth control.
Tubal damage is usually diagnosed by a hysterosalpingogram or laparoscopy.
Once an egg is fertilized and becomes an embryo it implants in the lining of the uterus (endometrium). The uterus expands to accommodate the growth of a developing fetus and it must be free of serious defects.
Fibroids, also known as fibromyomas, leiomyomas or myomas, are non-cancerous tumors that are outgrowths of the muscular wall of the uterus. Fibroids can become large enough to obstruct the uterus thus interfering with embryo implantation and the ability to carry a child to term.
Polyps are caused by an overgrowth of the tissue lining the uterus (endometrium). Many times polyps are small and do not interfere with embryo development. When they enlarge they can restrict the uterine cavity impairing implantation and development.
Some women are born with congenital abnormalities of the uterus such as the septate or bicornuate (two-horned) uterus which is heart shaped and divided into 2 cavities. Pregnancy can occur in many of these women; however, the miscarriage rate is much higher if a septum is present.
The cervix is the opening between the vagina and the uterus and it is lined with numerous small glands (cervical glands) which produce mucus.
Once sperm are ejaculated they swim through this mucus from the vagina through the cervix and into the uterus. The mucus also provides nourishment for the sperm. If the cervical mucus is inadequate, the sperm cannot reach and fertilize the egg.
Estrogen stimulates the production of cervical mucus and low levels of this hormone can lead to diminished or thickened cervical mucus which inhibits sperm transport.
The post coital (after intercourse) test is used to determine the ability of sperm to survive in the cervical mucus.
Severe reproductive tract infections, also known as pelvic inflammatory disease (PID), can be caused by microorganisms such as chlaymdia and gonorrhea. These infections can seriously damage the tubes, ovaries, uterus, and other organs within the pelvic cavity and can cause pelvic scarring or adhesions.
When a specific cause of a couple’s infertility cannot be identified it is called “infertility of unknown causes.” This does not mean that there is no reason for infertility, rather it cannot be diagnosed.
Great strides have been made in reproductive medicine over the last 10 years but much research remains to be done. The percentage of couples falling within this category will continue to decline as new causes of infertility are discovered.
Infertility Diagnosis
Infertility tests assess the processes that must occur for pregnancy to result.
Both male and female partners should be tested for infertility if pregnancy fails to occur after 1 year of regular unprotected sexual intercourse.
An analysis of the man’s semen should be performed before the female partner undergoes any invasive testing.
Laboratory Tests
Various tests are used to evaluate hormone function and ovarian reserve (the number of follicles and quality of the eggs).
Clomiphene citrate challenge tests may also be used to test for ovarian reserve.
Imaging Tests
Imaging tests such as ultrasound, sonohysterogram and hysterosalpingogram are used to examine your fallopian tubes and uterus.
Surgical Diagnostic Procedures
Hysteroscopy uses a long tube with a camera on the end which is inserted into the vagina and advanced through the cervix so the doctor can view the uterus, ovaries and fallopian tubes.
A laparoscopy is often performed to view and evaluate the reproductive organs. Many times conditions, such as endometriosis, can be treated during a diagnostic laparoscopy.
Infertility Treatment
Several approaches are used to treat female infertility:
- Drugs to induce ovulation, such as clomiphene and gonadotrophins
- Surgery to correct blockage in the fallopian tubes or other structural problems, such as uterine fibroids
- Assisted reproductive technologies (ART) such as:
- Lifestyle measures are also important. They include maintaining a healthy weight, quitting smoking, and timing sexual activity with ovulation cycle.
Treatment of “infertility of unknown causes” may consist of intrauterine insemination followed by IVF if pregnancy does not occur. Intracytoplasmic sperm injection will often be recommended since there could be an “unknown” male factor infertility component.