Fertility Infertility Issues

An estimated 7 million women in the United States experience infertility during their reproductive years, which the CDC considers to be ages 15 to 44. Medically, female infertility is defined as the inability to become pregnant in spite of having unprotected sexual intercourse for 12 consecutive months. Most reproductive specialists divide female infertility into primary and secondary categories. As will be explained, most cases of female infertility arise from secondary causes.

Primary causes of infertility include chromosomal abnormalities as well as certain genetic mutations. The main chromosomal disorder resulting in infertility is Turner syndrome, in which a female is born with a 45 XO karyotype. Most females with Turner syndrome are born without a uterus or ovaries and almost never undergo puberty without estrogen replacement therapy. Females born with Down’s Syndrome or Trisomy 21 are infertile around 50% of the time. Other genetic disorders in which a female’s uterus and/or ovaries fail to develop also result in infertility. One such condition, Mayer-Rokitansky-Kuster-Hauser-syndrome, is well described in the medical literature but tends to occur infrequently, in approximately 1 in 4,500 newborn females.

The most important secondary cause of female infertility is probably untreated sexually transmitted diseases, especially pelvic inflammatory disease, or PID. An estimated 750,000 women in the U.S. are diagnosed with PID each year. The two main bacterial culprits in PID are chlamydia and gonorrhea. Women who delay seeking treatment for either of these STDs risk permanent scarring of their Fallopian tubes, a condition called chronic salpingitis. Obstruction of the Fallopian tubes, in turn, dramatically raises a woman’s risk of an ectopic (tubal) pregnancy.

Disorders of the hypothalamic-pituitary axis can also result in infertility. The main one that affects women of reproductive age is prolactinoma, a tumor arising from lactotroph cells in the anterior pituitary. Mechanical compression by the tumor along with the excess prolactin it produces decreases FSH and LH release from neighboring pituitary cells, resulting in anovulatory menstrual cycles. Following surgical removal of a prolactinoma, a woman’s menstrual cycles and fertility usually return within a few months. Untreated hypothyroidism may also cause infertility.

Finally, certain gynecologic conditions may cause impaired fertility or overt infertility. These include leiomyomas (uterine fibroids), endometriosis, and polycystic ovary syndrome, sometimes called Stein-Leventhal syndrome in the older medical literature. The first two conditions generally involve the uterus and respond well to treatment. Uterine fibroids arise from smooth muscle tissue. Although these tumors are benign, they may grow large enough to interfere with embryonic implantation and placenta formation, thereby causing infertility. The main treatment for symptomatic fibroids in women who desire a future pregnancy is surgical excision (myomectomy).

The pathogenesis of endometriosis is not completely understood. This condition sometimes runs in families and is characterized by heavy menstrual bleeding and painful cramps. According to one theory, endometriosis occurs if the uterine lining is not fully shed during menstrual periods. Supposedly, the retained endometrial tissue travels along a retrograde path through the oviducts and into the abdominal cavity, where it implants on the ovaries or along the walls of the uterus.

Other scientists believe that some hormonal imbalance induces clusters of extrauterine cells to differentiate into tissue resembling the uterine lining, a process called metaplasia. These ectopic foci of endometrial tissue grow in response to estrogen and bleed into the abdominal cavity during menstruation. This may account for much of the pain and cramping associated with endometriosis. Regardless of its cause, endometriosis can be treated with oral contraceptives and other hormonal agents, and failing that, with surgery.    

Polycystic ovary syndrome (POS) is a different story altogether. This condition is marked by obesity, diabetes, acne, excessive growth of facial hair (hirsutism), and scant or irregular menses. POS tends to have an unpredictable course even in women whose menstrual cycles are stabilized with oral contraceptive pills. Surgical intervention, in which wedges of the ovaries are removed to allow for normal follicle rupture, sometimes restores fertility temporarily in women with POS. The fertility drug clomiphene (Clomid) also improves the chances of conception in women with this disorder.