Infertility
Infertility was once thought of as a “female problem” but we now know that there is a contributing male factor in up to 47% of infertile couples. Infertility is also more common than previously thought and occurs in approximately11% of couples at some time during their reproductive lives. Infertility in women under thirty-five years of age is defined as the inability to conceive after one year of unprotected intercourse. In women over 35, the time is shortened to six months.
More than ever, women are seeking reproductive care. It is not clear whether the incidence of infertility is increasing or if more females are seeking treatment because of increased awareness. There is some evidence that the incidence of male infertility has increased slightly in the general population.
The causes of infertility are complex and best evaluated by a Board Certified Reproductive Endocrinologist. These specialists complete a Residency in Obstetrics and Gynecology and then pursue at least two years of advanced infertility training in an accredited Fellowship program. This training includes clinical diagnosis, medical management, assisted reproductive technologies, and extensive microsurgical experience.
Fortunately, many treatment options are available and approximately 85% of couples who receive appropriate care will conceive. Most couples do not require advanced reproductive technologies, such as in vitro fertilization, and achieve pregnancy with medication, surgery, or procedures such as intrauterine insemination. As females’ age, the likelihood that IVF will be needed increases which reinforces the need for rapid evaluation and treatment.
A complex series of biologic events must occur for pregnancy to result.
1) The ovary must contain eggs that will develop to maturity within the ovarian follicles under the influence of follicle stimulating hormone.
2) The egg must be released (ovulated) from the follicle and travel through an open fallopian tube to the end nearest the uterus where fertilization occurs.
3) 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.
4) The sperm must travel through the vas deferens and urethra and be ejaculated into the vagina.
5) Once deposited, the sperm must swim thorough the cervical mucus into the uterus.
6) 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 compliment of chromosomes.
7) 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.
8) Once the embryo implants its nourishment and development are supported by progesterone and other hormones.
9) The uterus must be capable of supporting the growing fetus.
When one or more of these processes are impaired, infertility can result. Several major categories of infertility relate to the nine processes above.
1) Male factor infertility- Male infertility occurs when a sufficient quantity of viable sperm cannot be produced and ejaculated into the vagina. Sperm characteristics such as shape, ability to move in a straight line, and others are important for fertilization.
The sperm must be able to swim to the egg and once there initiate fertilization. Intrauterine insemination is often a treatment of first choice for mild male factor and IVF with intracytoplasmic sperm injection is used in more severe cases.
2) Cervical Factor- Sperm swim through, and are nourished by, the cervical mucus which is produced by the cervical glands. If there is not enough mucus, or it is too thick, sperm cannot reach the uterus. This condition is commonly treated with intrauterine insemination.
3) Antisperm antibodies- The body normally produces antibodies to destroy invading organisms such as bacteria or viruses. Sometimes the female’s immune system mistakenly identifies sperm as harmful and seeks to destroy them.
Rarely, a man will produce antibodies to his own sperm usually because of contact between his blood cells and sperm, as through injury to the testicles. Intrauterine insemination is often used to treat couples with antisperm antibody reactions.
4) Ovarian factor/Ovulatory Dysfunction- Women are born with their full compliment of eggs at birth. During each monthly menstrual cycle, an egg is recruited and develops to maturity within an ovarian follicle. Once the egg reaches maturity it is ovulated.
These events are under the control of several hormones primarily FSH, LH, estrogen and progesterone. The hypothalamus (a gland at the base of the brain) secretes gonadotropin releasing hormone which stimulates the pituitary to release FSH and LH. FSH causes the recruitment of follicles and supports the developing egg. As the follicles develop, the levels of estrogen rise and when they mature LH signals ovulation. Ovulatory dysfunction (irregular or no ovulation) is most often due to hormonal imbalances and is usually treated with medications such as Clomid or FSH. Rarely a woman is born without ovaries or with eggs that will not fertilize for unknown reasons.
5) Uterine factor- The uterus must be of an appropriate size and shape to support the developing fetus. Sometimes women are born with a misshapen or absent uterus. The uterus can also be damaged by severe infection, endometriosis, polyps or fibroids. When surgical treatment fails, a surrogate mother must be used.
6) Endometriosis is a common cause of infertility and pelvic pain. Endometriosis occurs when the cells that normally line the uterus (endometrial cells) enter the pelvic cavity and attach to organs such as the tubes, uterus, ovaries, diaphragm, etc. Once attached, the endometrial cells grow and can penetrate and obstruct the organ. For example, endometrial cells can attach to the tubes and cause blockage. Endometriosis can also create inflammation in the pelvic cavity which is believed to impair fertility.
7) Tubal disease- The mature egg must travel from the ovary to the uterus through an open fallopian tube. The tubes can be blocked by conditions such as endometriosis, scarring, or severe infection. Some women seek to have previous tubal sterilization procedures reversed. When the tubes are severely damaged IVF is the treatment of first choice.
8) Unexplained- Sometimes no specific cause of a couple’s infertility can be identified. This category becomes smaller as researchers continue to discover the many processes involved in successful conception.
Many tests for infertility are discussed in detail throughout our Web site. We also describe the most common treatments for the various causes of infertility. Our goals are to insure that each couple fully understands the medical condition(s) causing their infertility, the available treatments, and the probability of success.