Author's Note: The expert advisors for this conference are James M. Goldfarb M.D., M.B.A., Director of Fertility Services, and Professor of Obstetrics & Gynecology at the Lerner College of Medicine, Cleveland Clinic Foundation, and Sandra P. Stewart, R.N., M.S., Clinical Nurse Specialist and Nurse Manager, both at the Cleveland Clinic Fertility Center in Beachwood, Ohio. Sandra Stewart is also my sister-in-law.

Currently, in Western countries, about 10-15% of couples experience some difficulty with fertility.(1) Remedies range from a visit to a primary physician, education and adjustments in timing attempts to conceive, to placing the entire reproductive process under specialty control.

The causes of infertility may vary, depending on the population examined. Are you looking at everyone with a fertility problem or are you looking at those who consult specialized facilities? In terms of the overall causes of fertility problems, the figures usually given are 30-40% male factor, 30-40% female factor and the remainder, combinations of both members of the couple or not identifiable by any current method. The Federal Centers for Disease Control (CDC) collcts data (on treatment cycles) from fertility clinics on the special population of patients using assisted reproductive technology. Their latest figures, for women under 35, categorized causes as 40% female, 23% male, 17% combined male and female factors, 10% more than one female factor and 10% unexplained by any definable cause.(2)

What is Infertility, Subfertility, Sterility?

Different words are used to define different situations. Definitions have changed, as technology has changed.

Sterility is the absolute inability to procreate: an absent uterus in women, absent testes in men. In years past, a woman with blocked fallopian tubes or man with an obstructed vas deferens would be sterile. But with assisted reproductive technology (ART), this is no longer the case.

Infertility is usually defined as no pregnancy after one year of unprotected intercourse. This is a relative measurement. Over time, many couples may achieve pregnancy. In five years, nearly one half of "infertile" couples will conceive.(1)

Subfertility is used to describe gradations between normal fertility and sterility, often used interchangeably with infertility.

Fecundability is the pregnancy rate from one menstrual cycle. The normal rate in humans is 20%. Seventy-five percent of normally fertile couples are expected to have conceived in six months and almost 100% by one year.(1)

Normal fertility can be considered from several different points of view: the couple, the female and the male. In this Cyberounds^® we are going to look at female fertility: the biological steps and mechanisms, the defects, the causes of the defects and what to do.

Case Report

July 25, 2003 was the twenty-fifth birthday of Louise Brown, the first baby born after in vitro or assisted reproductive technology. In an article that took up two-third's of a column in the Lancet, Steptoe and Edwards told of their patient, Mrs. Brown, who had come to see them in 1976. She was 28 at the time and had been attempting to get pregnant for the previous seven years. She had been found to have occluded fallopian tubes and had tubal surgery and excisions of the tubal ampullae but the blockage persisted. They did a laparoscopy in February 1977 and found distorted tubal remnants, tubal occlusion and peritubal as well as ovarian adhesions. Six months later, they did a laparotomy, excised the tubes, lysed the adhesions and suspended the ovaries in a position allowing for oocyte retrieval. In November 1977, an oocyte was recovered, fertilized in vitro and implanted in the uterus at the 8-cell embryo stage. The 2700 gram girl was born at 38 weeks, five days, by C-section. The mother had pre-eclamptic toxemia with elevated blood pressure, edema, albuminuria and elevated uric acid.

Today, specialists in the field of Assisted Reproductive Technology (ART) will marvel at the great good luck the authors had in getting a successful outcome, given the technology, medications and plain old know-how that was not available at that time. But I want to concentrate on Mrs. Brown. She was a woman with normal eggs and blocked tubes, one of the most important causes of female infertility.

There are really three basic questions that have to be answered when you approach a woman with problems getting pregnant.

1. Is she ovulating?
2. Is there a clear passage from the ovary to the uterus?
3. How old is she?

A similar set of questions has to be answered in men. Is there sperm? Can it be delivered to the female? Is the sperm normal? In the male these questions are answered in a preliminary and rather thorough way by semen analysis. With women the process is more complicated. Before we look at causes and treatments, let's start with basic female function.

Normal Female Fertility

Oogenesis

The female germ cells, called oogonia, lodge in the cortex of the ovary. They divide rapidly and at the fifth month of fetal life number up to 6-7 million cells. At that time, they begin maturation, completing the first phase of meiotic division, but arrest development before the first division of meiosis. These cells are now called primary oocytes and are in the "germinal vesicle stage." These cells are tetrad - they have four copies of each chromosome -- and are ready for the first division of meiosis that will yield two diploid daughter cells.

The primary oocyte, with its surrounding single layer of granulosa cells, is called the primordial follicle. In fetal life, these primordial follicles rapidly decrease in number to 2-4 million at birth. They continue to degenerate in prepubertal childhood until, by puberty, there are about 400,000 of these follicles in the ovaries.(3) It has been generally accepted that these are all the germ cells a woman has for her lifetime because these cells have not been known to multiply during life the way the spermatogonia do. Although there is one recent article that suggests that germ cells in the ovary may be able to regenerate later in life,(4) in humans, for all practical purposes "what you have at birth is what you get for life" is still the case.

Follicle Development and Ovulation

Throughout female life from menarche to menopause, a small number of these primordial follicles are constantly beginning development. The primary change is an increase in the numbers of granulosa cells around the primary oocyte. These changes are not mediated by pituitary hormones but by local factors in the follicle. The follicle is now called the primary or preantral follicle. These follicles are now ready for further development mediated by pituitary hormones. Without the influence of pituitary hormones, these primary follicles will become atretic.

At puberty, the hormones of the hypothalamic/pituitary axis start to influence ovarian function. In response to gonadotropin releasing hormone (GnRH), follicle stimulating hormone (FSH) and luteinizing hormone (LH) are secreted. FSH stimulates aromatase production in the granulosa cells and they, in turn, secrete estradiol. FSH also directly induces rapid mitosis of the granulosa cells, while the estradiol increases the number and sensitivity of the FSH receptors on the granulosa cells.

One or two of the primary follicles begin rapid development and, because of their heightened sensitivity to FSH, become dominant. As the estradiol level increases, negative feedback on GnRH decreases FSH secretion, and the other primary follicles become atretic. Despite decreased levels, the FSH effect on the dominant follicles is still strong because of their many granulosa cells and numerous FSH receptors.(3)

The Antral Follicle

As the follicle develops, more and more fluid spaces appear in it until the antral follicle becomes a cyst-like structure with the oocyte surrounded by granulosa cells fastened to one edge. The follicle is called antral because of the large cell free space that has developed (from the Latin antrum, cavity or chamber). The average diameter of this preovulatory dominant follicle is 19.5 mm (range 18-25 mm), a size easily detected on ultrasound.(3)

Ovulation

With respect to the ovary, the menstrual cycle is divided into two phases: the follicular phase and the luteal phase. The follicular phase, as just described, is dominated by the development of the follicle under the influence of FSH. As the granulosa cells become more numerous, they express more receptors for luteinizing hormone (LH). At the same time, the GnRH pulses from the hypothalamus become increasingly frequent and additional luteinizing hormone is secreted. LH, in turn, stimulates the granulosa cells to secrete progesterone.

The combination of high levels of estradiol and rising progesterone exert a positive feedback on the pituitary to secrete both FSH and LH. They both rise to a peak concentration 24-48 hours before ovulation. Because of the short half-life of LH, the LH peak is the most accurate predictor of ovulation. LH and FSH cause the production of prostaglandins and proteolytic enzymes that disrupt the follicle and release the ovum, or egg, from the ovary. This release into the peritoneal space at the fimbriated end of the fallopian duct is called ovulation.

As ovulation occurs, the egg undergoes the first meiotic division, producing two diploid cells. One is small and nonfunctional and, as it is divided off from the main cytoplasm, remains under the zona pellucida. It is called the first polar body. As the sperm enters the egg, the second meiotic division, producing two haploid cells, takes place. One of these cells, the second polar body, is divided off and settles next to the first polar body. The remaining haploid cell is ready to combine with the haploid sperm to form the diploid zygote.

After ovulation, as the follicle collapses, the remaining cells hypertrophy and accumulate lipid, giving them a yellow color, forming the corpus luteum (from the Latin luteus, yellow). The cells of the corpus luteum secrete progesterone, which in turn causes the glands in the endometrium to accumulate and later secrete glycogen. Glycogen will nourish the free-floating blastocyst until it implants. Progesterone also inhibits uterine contraction. With respect to the uterus, the menstrual cycle is also divided into two phases: the proliferative, before ovulation, when the glands are building up, and the secretory, just described, after ovulation.(3)

Causes and Mechanisms of Female Infertility

I would like to give you a feel for the relative incidence of the causes of female factor infertility. The task is hard because the population presenting to the primary care office is different from the population presenting to fertility specialists and specialty centers. There is agreement on the main causes: ovulation disorders, tubal disease and endometriosis.

In a population of infertile couples, if you consider unexplained and male factor infertility at about 25% each, ovulatory disorders and tubal factors would be about 20% each and endometriosis 5-10%, with small percentages for uterine/cervical problems.(3)

The history and physical exam offer us many hints about the cause of infertility (Table 1):

First Question: Is She Ovulating?

Defects in ovulation comprise about 25% of female fertility problems. The biggest clue that ovulation is occurring is the periodicity of menstruation. Regular periods are almost always associated with ovulation. Irregular or scanty menstruation (oligomenorrhea) or absent periods (amenorrhea) have to be worked up. Amenorrhea can be primary (no menarche, no periods ever) or secondary (periods were present, then stopped altogether long before the age of likely menopause).

It is impossible to describe all the conditions that affect ovulation, but let me hit the highlights and give you some examples of the mechanisms involved. Causes for ovulatory defects can be genetic, as in Turner's syndrome, or hormonal, as in prolactinoma or the polycystic ovary syndrome (PCOS). Deficient or excessive body fat can also lead to hormonal changes causing anovulation.

Turner's Syndrome

Although most of these women are identified in infancy or childhood, a few may present for evaluation of infertility or for recurrent pregnancy loss. The classical musculoskeletal features of Turner's -- short stature, increased carrying angle of the arms, webbing of the neck -- may be present and are clues to the diagnosis.

The classic chromosomal defect in Turner's is the absent X chromosome, karyotype 45,X, although mosaicism (e.g., 45,X/46,XX) and many other combinations, as well as second X chromosomes with deletions can also result in the syndrome. For our purposes, the extremely poor development of the ovaries, the gonadal dysgenesis, is the key feature. The number of primordial follicles is decreased and there is increased apoptosis of these follicles.

The majority of Turner's syndrome cases are diagnosed before childbearing is contemplated -- at birth, during mid-childhood because of short stature or at expected puberty when they fail to develop. These latter patients may be supported with estrogen replacement to establish secondary sex characteristics and optimal uterine development. Overall, 90% of patients will require hormone replacement.

The ability to produce eggs and support a pregnancy depend very much on the amount and quality of the ovarian tissue present. Some patients develop normally but when spontaneous pregnancy does occur, there is a high risk of chromosomal abnormalities in the fetus and recurrent pregnancy loss. Most patients will experience early ovarian failure. Patients with a normal uterus, either through normal development or estrogen support, may be able to achieve a pregnancy with donor eggs.(5),(6)

Because coarctation of the aorta is another congenital defect that can be present in Turner's syndrome, any woman diagnosed with Turner's syndrome and considering pregnancy needs a preliminary full cardiac workup because coarctation can make pregnancy very hazardous, even fatal.

Polycystic Ovary Syndrome (PCOS)

This syndrome gets its name from the enlarged ovaries with many subcapsular cysts seen in the originally described patients. Many of us first heard of this syndrome as the Stein-Leventhal syndrome, described in 1935, and additionally characterized by amenorrhea, hirsuitism and obesity. The 1990 NIH Consensus Conference defined PCOS as oligomenorrhea and hyperandrogenism in the absence of other endocrine disorders such as congenital adrenal hyperplasia or hyperprolactinemia. Amenorrhea, hirsuitism, obesity and even polycystic ovaries are not required to make a diagnosis of PCOS.

Endocrine features have been observed that can explain the excess androgen. Tonically increased levels of LH (that may result from abnormal GnRH secretion) will enhance ovarian theca cell production of androgen.(3) Elevated insulin levels, especially in obese patients, can increase ovarian and adrenal androgens and decrease sex hormone binding globulin (SHBG) secretion by the liver. The net effect is increased active androgen in the ovary and the circulation, inhibiting oocyte development.

Increased insulin sensitivity (which leads to lower insulin levels) by weight loss or medication can permit ovulation in some of these women. Although not an approved indication, metformin, which increases insulin sensitivity, has been used alone or prior to ovarian stimulation to treat infertility.(7)These patients do have adequate germ cells. In fact, one investigator believes there are excessive primordial follicles in the ovary in these patients.(8) The hormonal milieu of increased insulin and androgen prevents complete maturation of oocytes in the follicular phase, but when the milieu is corrected, mature oocytes can be obtained and ovulation can occur.

Hyperprolactinemia and Prolactinoma

Prolactin is a pituitary hormone made by the lactotrophs, a population of chromophobe cells in the pituitary. Its main function is to stimulate breast development and milk production during and after pregnancy. The neurotransmitter dopamine regulates prolactin production through inhibition. In other words, when dopamine interacts with lactotrophs, prolactin secretion is inhibited. Any influence that decreases the effect of dopamine or increases the lactotroph cell mass can result in excess prolactin secretion.

Adenomas consisting of lactotrophs are known as prolactinomas and cause what is considered primary hyperprolactinemia. Secondary causes would be drug inhibition of dopamine receptors, compression of the pituitary stalk or gland by another tumor or conditions that cause elevated growth hormone or thyroid stimulating hormone.

Excess prolactin has several effects that can interfere with ovulation: decreased secretion of GnRH, inhibition of LH and FSH release, and inhibition of both estrogen and progesterone secretion in the ovary. Besides amenorrhea and infertility, women with elevated prolactin may experience galactorrhea (spontaneous flow of milk from the nipple). Headaches and neurological symptoms may presage significant, usually nonprolactinoma, tumors.

Normal blood prolactin levels are around 25 micrograms in women. A level up to 100 micrograms is often from secondary causes -- medication, physical compression or another endocrine condition. Higher levels are most often associated with prolactinomas.

A thorough workup should be done to rule out the secondary causes. To diagnose prolactinomas, the best test currently available is the gadolinium-enhanced MRI. Prolactinomas are divided arbitrarily by size into microadenomas, less than 10 mm in diameter, and macroadenomas, more than 10 mm in diameter.

Elevated prolactin is treated with the dopamine agonists, bromocriptine and cabergoline. Bromocriptine is preferred in fertility treatment because of its safety record in pregnancy. (3),(9).

Body Weight and Fertility

Both excess and deficient body weight are associated with infertility in women. In obesity, the mechanism is probably similar to that of PCOS. Insulin resistance and high insulin levels stimulate androgen production and decrease sex hormone binding globulin (SHBG), resulting in higher effective free androgen levels that inhibit follicular development. Weight loss restores fertility. Increasing insulin sensitivity with metformin or the thiazolidinediones can also be effective.(3),(7)

Women who are extremely thin can also experience amenorrhea. They have low gonadotropin and estrogen levels, as well as absent periods. Because deficient GnRH secretion is thought to be responsible, this type of amenorrhea is called hypothalamic, or functional. These women have low body fat stores and/or energy deficits without any other demonstrable cause for a GnRH deficit. The most common conditions are starvation, abundant exercise or eating disorders.

Currently, investigators think that the mediator for this effect is the fat cell hormone leptin. The amount of circulating leptin is proportional to the fat cell mass. A critical amount of leptin is required for menarche in girls. Slender women with this type of amenorrhea have lower leptin levels than matched controls. A recent study showed that recombinant leptin increased LH and estradiol, and induced follicular development and even ovulation in some patients with amenorrhea secondary to strenuous exercise or low body weight.(10)

Summary of Ovulation Disorders

In chromosomal disorders, e.g., Turner's syndrome, the key feature is ovarian dysgenesis with fewer follicles, deficient estrogen production, poor uterine development and early ovarian failure.

In Polycystic Ovarian Syndrome (PCOS) and obesity, insulin resistance and elevated insulin levels start a process that results in increased ovarian and circulating androgens that inhibit follicular development.

Hyperprolactinemia decreases all the hormones involved in follicle maturation and ovulation: GnRH, FSH, LH and ovarian estrogen and progesterone.

In women with remarkably decreased fat cell mass, the cause of anovulation is low levels of the fat cell hormone leptin, which is required for normal GnRH secretion.

Second Question: Is There A Clear Passage From the Ovary to the Uterus?

The two main conditions that can affect the fallopian tubes are endometriosis and tubal infection.

Endometriosis

In this condition, implants of endometrial tissue are found outside the uterine cavity, primarily in the pelvis, on the ovaries, tubes, peritoneum and adjacent organs of the GI and GU tracts. This extra endometrial tissue responds to cyclical estrogen and progesterone in the same way the uterine endometrium does -- proliferating, swelling and bleeding. The implants can invade the surrounding tissues, affect nerve endings, and cause scarring and adhesions on adjacent peritoneal surfaces.

The most common symptoms of endometriosis are pelvic pain, dysmenorrhea and dyspareunia. These symptoms generally coincide with menstruation but can become chronic. That said, there are women who have had no complaints at all and are found to have endometriosis at laparoscopy or laparotomy.

The severity of endometriosis is divided into stages that depend on the size and depth of the endometrial implants and the thickness of the adhesions. Sizable masses, called endometriomas or chocolate cysts, can develop as cystic structures. The stages are:

1. minimal, with a few superficial implants;
2. mild, more numerous implants, filmy adhesions;
3. moderate, more numerous and larger implants, dense adhesions; and
4. severe, more dense adhesions, larger implants, endometriomas.

In Stages III and IV the adhesions can cause distortion of the oviduct.

There is no dispute that Stage III and IV endometriosis, with distortion of tubal anatomy and involvement of ovarian surfaces, can cause infertility. Studies have shown that surgical treatment can improve fertility. But whether endometriosis in its minimal or mild forms has any effect on fertility is in dispute. Many studies have shown that treatment resulted in no improvement in fertility, while others have demonstrated a benefit.(3),(10) This controversy notwithstanding, treatment of endometriosis to prevent progression to more severe stages and to address pain symptoms is certainly indicated at any stage.

Surgical treatment by laparoscopy or laparotomy aims to destroy implants by electrocautery or laser, to lyse adhesions, and evacuate or remove cysts. The goal is to restore normal anatomy to allow fertilization to occur. Medical treatment (i.e., hormonal therapy) has not been shown to restore fertility. The aim of hormonal therapy is to relieve pain and decrease or eliminate extra-uterine implants. The therapy suppresses cyclical hormone secretion and, of course, ovulation, and often induces an artificial menopause. Androgens, tonic GnRH, birth control pills, progesterone alone, selective estrogen or progesterone receptor inhibitors or aromatase inhibitors have all been used in the treatment of endometriosis. (3),(10)

Pelvic Inflammatory Disease (PID)/ Salpingitis

PID is the most common cause of tubal factor infertility. The infection involves the upper genital tract (the uterus, the fallopian tubes and the ovaries) and structures around these organs. The infection of the fallopian tube (salpingitis) is the most crucial element causing infertility. The fallopian tube travels through the upper lateral portion of the uterine wall, extends laterally and drapes down and over the ovary. Its widened distal end has many projecting folds, the fimbria, some of which are in direct contact with the ovary. The tube is lined with a mucosa containing special, ciliated cells that direct the egg toward the sperm and the fertilized egg into the uterine cavity. Infection can destroy the mucosa and distort and/or occlude the tube.

The main bacterial culprits are Neisseria gonococcus (NG) and Chlamydia trachomatis (CT). NG is directly cytotoxic to the tube mucosa; CT probably destroys cells through immunological mechanisms. Classic acute pelvic inflammatory disease (PID) associated with either or both of these organisms is polymicrobial and intensely inflammatory, with mucopurulent exudates that can also involve the ovary and the pelvic peritoneum. The tubes can become thickened, distorted and occluded. Abscesses can form between the tube and the ovary or in the adjacent pelvis, and can be life threatening.

This condition requires prompt, broad-spectrum antibiotic treatment. Interestingly, in about half of cases of tubal infertility secondary to PID, there is no history of acute infection. Chlamydia in particular can linger in the genital tract, causing ongoing subclinical damage. Chronic pelvic pain, infertility and ectopic pregnancy are the serious sequelae of PID.(3)

PID is an ascending infection from the lower genital tract. It results primarily from infections described above and contracted from the male partner. A small percentage of cases are iatrogenic. Risk factors are youth (75% of infections at age 25 or younger), menstruation, multiple partners, no contraception, a history of a sexually transmitted disease and surgical instrumentation. A previous episode of PID increases the likelihood of a subsequent infection. Teenagers are particularly susceptible because of immature cervical anatomy. Oral contraceptives are protective because they thicken the cervical mucus and shorten the menstrual periods. Barrier contraceptives interrupt transmission; spermatocides can also be microbicides.

For a long time, the intrauterine device was thought to increase the likelihood of PID. Recent evidence shows that risk is increased only during the first 20 days after insertion. Earlier reports reflected the complications secondary to the Dalkon Shield, implicated in several deaths from tuboovarian abscess. The currently used copper and progesterone IUDs have not been associated with such complications.(11)

It is better to avoid PID than confront its sequelae. Because of improved testing procedures, we now know that Chlamydia is the most common pathogen, with four times the incidence of NG. In high-risk populations, the two infections are frequently seen together. Blood and urine tests for both NG and CT are now available. Cervical sampling can be done at the time of a pelvic exam and is routine in populations where risk is high.

Infection should be treated promptly and thoroughly, covering both NG and CT, because of the risk of subclinical CT in the upper tract. Single dose regimens are useful when there is a question about compliance or follow up opportunities. It is crucial to treat the infected partner in order to prevent recurrent infection. When there are clinical signs of PID, physicians should develop a very low threshold for the treatment of acute pelvic pain, especially in high-risk populations. Treatment regimens are subject to frequent updates because antibiotic-resistant strains emerge. The CDC is the best source for current guidelines.(12)

The key diagnostic tests for PID sequelae are hysterosalpingogram (HSG) and laparoscopy. In HSG, water-soluble radioopaque dye is injected into the uterine cavity. Normally, it courses through the fallopian tubes and into the peritoneal cavity. The procedure will detect distortions and obstruction of the uterine cavity and the fallopian tubes, as well as delineate the typical tubal mucosal pattern.

Laparoscopy examines the anatomical appearance and relationships of the tubes and ovaries, and locates adhesions and masses. A formerly infected tube may be dilated and contain sterile fluid -- called a hydrosalpinx. The fimbria may be scarred and club-shaped, and the normal rugal folds of the tube obliterated. The ovary may be covered with adhesions, or there may be dense adhesions between the tube and ovary associated with a scarred mass -- called a tubo-ovarian complex.

Based on observations from the diagnostic procedures, investigators have developed criteria for severity of the PID sequelae, much like endometriosis. In mild disease, the rugal pattern of the tube is preserved and the fibria are normal, though they may be inverted or stuck together by adhesions. In moderate and severe cases, the rugal pattern is lost, the fibria are distorted, the tube is occluded and dilated (the hydrosalpinx) and the thickness of the tubal wall is increased. Adhesions can involve the surface of the ovary and adjacent pelvic structures; the most severe form is called the "frozen pelvis."

In very mild cases, the performance of the salpingogram may, by itself, open the tube. Surgical treatment, usually by laparoscopy, seeks to open the tube and free the distal tube and ovary of adhesions. In mild disease, lysis of adhesions and freeing up the fibria can result in pregnancy rates of 60-75%. In more severe disease, the rates plummet and the ectopic pregnancy rate rises sharply. The bottom line is that if there is great destruction of the tubal epithelium and anatomy, fertilization (which takes place in the distal half of the tube) is less likely, and abnormal implantation and ectopic pregnancy are more likely to occur.(3)

Operative intervention for severe disease is generally reserved not for treatment but for removal of fluid filled fallopian tubes (hydrosalpinges) prior to in vitro fertilization (IVF). It has been shown that the presence of hydrosalpinges reduces the success rates of IVF by as much as 50%.

The Role of Surgery in Endometriosis and PID

It is interesting to contrast the role of surgery in endometriosis and PID for the purpose of restoring fertility. In endometriosis, current opinion holds that treatment of mild disease is not likely to enhance fertility but treatment of moderate or severe disease will. In PID, treatment of mild disease is likely to improve fertility but treatment of moderate or severe disease is much less effective and incurs a high risk of ectopic pregnancy, so that in vitro fertilization is preferred.

Third Question: How Old Is She?

To get a good idea of the decreasing fertility of women over the decades, take a look at the 2002 CDC statistics on assisted reproductive technology success rates. Nationally, live birth rates are 37% for women <35 and 4% for women >42.(14) (Remember: this is a select group, those patients who attend fertility clinics, not the general population.)

As mentioned earlier, there are a finite number of primordial follicles present in the ovary at birth and they decrease steadily until the time of menarche, from 2-4 million to 400,000. With every cycle, primordial follicles are lost. As women age, more chromosomal abnormalities occur during cell division of the ova. The decreasing numbers of follicles, anovulatory cycles and poor quality of the ova all combine to diminish the fecundability of women, especially after age forty.(14)

While age is the most predictive parameter regarding a women's ovarian function, there are some tests that are also helpful. They are the follicle count, which is determined by ultrasound, and the blood tests for FSH and estradiol. All these tests are performed on or about the third day of the menstrual cycle. Follicle count is used because the number of small follicles seen on Day 3 gives a good idea about ovarian reserve, and some experts feel that this test is more sensitive than Day 3 FSH and estradiol.

The hormone levels give indirect evidence about ovarian reserve because inhibin, secreted by the granulosa cells of the follicles, operates in a closed loop feedback with FSH. As the follicle number diminishes, there are fewer granulosa cells producing inhibin and FSH increases. As granulosa cells continue to diminish, ovarian estrogen decreases despite elevated FSH. A high FSH and a low estrogen indicate severe loss of follicles.

Maximizing Female Fertility

Inducing Ovulation

Several drugs can be used to induce ovulation. The most common, and only FDA approved oral agent, is clomiphene citrate (Clomid^® or Serophene^®). Clomiphene is a weak estrogen that occupies estrogen receptors in the hypothalamus and thus interferes with the negative feedback of endogenous estrogen on GnRH release. GnRH continues to be released and stimulates FSH and LH. Another oral agent that has been used for the last several years, although not FDA approved for ovulation induction, is letrozole (Femara^®), an aromatase inhibitor. Letrozole directly lowers the production of estradiol from the ovary. Oral agents are generally the first line treatment for ovulatory dysfunction.

When oral agents do not work, injectable medications consisting of gonadotropins, either FSH alone or a combination of FSH and LH, can be used. Gonadotropin therapy is associated with a higher incidence of the most significant adverse effect of ovarian stimulation - multiple pregnancy. With the gonadotropins, the incidence of triplets is 8-10% and the incidence of quadruplets and higher is 1-2%, especially in younger women. These "high order multiple pregnancies" carry enormous risks, both to the mother and to the offspring. For example, among triplets as compared to singletons, the incidence of cerebral palsy is 30-fold higher.

Another rare, but significant, consequence of ovarian stimulation (more common with the gonadotropins than with clomiphene) is the ovarian hyperstimulation syndrome (OHSS). This syndrome ranges from abdominal pain caused by enlarged ovaries, to GI symptoms, to increased vascular permeability and ascites. In its most severe form, the woman can experience profound intravascular fluid loss and its sequelae. Exactly how this syndrome occurs is still not known, but two recent articles described genetic alterations in hormone receptors that resulted in OHSS during pregnancy. In these cases, the mutant receptor for FSH was also activated by the human chorionic gonadotropin (hCG) produced during the pregnancy.(15),(16)

Donor Eggs

Women who are not conceiving because of diminished ovarian reserve are quite capable of carrying a pregnancy to term and their live birth rates, using eggs harvested from donors, are similar to the rates for younger women.(14) There are three sources of donor eggs:

1. known donor -- friend, relative
2. shared donor -- younger woman going through IVF for herself shares her eggs with a woman who cannot make eggs
3. Anonymous paid donor -- women who are recruited to donate eggs and are paid for their time and effort.

Cryopreserving and Reimplanting Ova or Ovarian Tissue

Chemotherapy and radiation therapy destroy ovarian germ cells and can produce infertility. Cryopreserving fertilized ova, or embryos, can be done on embryos produced before cancer treatment. It is possible to cryopreserve ova, although they are, compared to sperm, much more susceptible to deterioration. This technique is considered experimental at present.

Women who are to receive pelvic irradiation can have a procedure called ovarian transposition. Their ovaries are laparoscopically moved out of the field of radiation so the radiation does not destroy their ovarian function. Another procedure, still in the experimental stage, is cryopreservation of ovarian tissue. Recently, researchers described the first live birth resulting from ovarian tissue that was removed prior to chemotherapy, cryopreserved and then reimplanted in a woman's pelvis after her treatment for Hodgkin's disease.(17)

Summary and Conclusions

Female fertility can be limited or diminished or destroyed in a number of ways. Women have a finite number of germ cells and follicles that are available for a limited period, from menarche to menopause, during their lifetimes. The process of ovulation is mediated by the interactions of hypothalamic, pituitary and ovarian hormones. Interference with ovulation can occur at any one or combinations of these sites. The oviducts can be distorted or blocked by the sequelae of endometriosis or infection. The quality of the ova and spontaneous pregnancy decrease steadily with age. Drugs are available that stimulate ovulation and donor eggs can be used. The cryopreservation of ova or ovarian tissue are techniques now receiving research attention.