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Infertility Causes

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Infertility is much more common than previously supposed.  In fact, the American Society for Reproductive Medicine (ASRM) reports that approximately 12 percent of all reproductive age couples experience infertility. The ASRM defines infertility as the absence of pregnancy after one year of regular intercourse for women less than 35 years old, or no pregnancy after six months for women older than age 35.

Visit the infertility treatments section to reads the latest treatments recommended for the conditions below. 

Testing Both Partners

Infertility is often thought of as a female problem; however, we now know that almost half of all infertile couples have a male infertility component. Therefore, we evaluate both partners for infertility causes at the outset. Male infertility can range from slight declines in sperm quality or quantity to complete absence of viable sperm.  For this reason, an infertility work-up always involves testing both partners.

Determining the Causes of Infertility

Infertility has a variety of causes, commonly classified by the organ system affected. For example, infertility caused by tubal factor results when there are conditions that interfere with the eggs' successful transport through the fallopian tubes from the ovaries to the uterus. Other infertility causes include uterine factor, cervical factor, ovarian factor, ovulatory disorders, endometriosis, unexplained infertility, and male infertility.

Some Causes of Infertility

Cervical Factor Infertility

The cervix is located at the juncture of the vagina and the uterus and it contains cervical glands that produce mucus to support the sperms transit and provide nourishment. If the uterus is a “bottle”, the cervix is the neck, allowing sperm to enter, and eventually for a baby to exit.

When the mucus is insufficient, “too thick,” or contains antisperm antibodies, it can impede, or “kill” the sperm. When this occurs very few sperm will reach the egg(s) and fertilization is unlikely.

The cervical mucus may contain antisperm antibodies that can incapacitate or “kill “sperm. Antibodies are produced by the body in response to invading pathogens such as virus or bacteria. The immune system produces these antibodies to target the “invaders” as a first line defense against disease.

Sometimes the immune system mistakenly identifies sperm as an invading pathogen and seeks to destroy them. Numerous “dead” or immobile sperm in the cervical mucus is an indication of the presence of antisperm antibodies. The post coital test is sometimes used to measure sperm quality/quantity after intercourse. The couple has intercourse at home and the patient comes to our office where a sample of her cervical mucus is examined under the microscope.

Fortunately, cervical mucus problems can usually be treated successfully using intrauterine insemination (IUI). In IUI, a catheter is used to place washed and concentrated sperm directly into the uterus thus avoiding cervical mucus “problems”. “Unwashed” sperm must never be used in IUI as severe, or even fatal, allergic or inflammatory reactions can result.

Often IUI is augmented by the administration of follicle stimulating hormone (FSH) and is known as stimulated IUI. FSH causes the recruitment and development of several follicles, each of which contains an egg. Once the eggs mature an injection of hCG or LH is given to cause multiple ovulations and the insemination is timed. Stimulated IUI should only be performed by a trained infertility specialist due to potential medication side effects and the increased incidence of multiple births.


The lining of the uterus contains endometrial cells that normally increase during the ovulation cycle so that the endometrium (lining of the uterus) is prepared to accept and support a developing pre-embryo.

Endometriosis occurs when the endometrial cells move through the Fallopian tubes, enter the abdominal cavity, and attach to organs such as the uterus, fallopian tubes, or ovaries. Endometriosis has been found in most parts of the body including the lungs and brain, so there may be other methods for its growth outside the pelvis.

Endometriosis can grow and spread rapidly under the influence of estrogen. Endometriosis can attach to organs, or other structures, and continue to grow and divide often damaging or penetrating the organ. For example, endometriosis can attach to, penetrate, or completely block the fallopian tubes.

When the immune system attacks endometrial cells it creates an inflammatory environment in the pelvic cavity which can sometimes interfere with normal fertility.

Endometriosis is thought to be caused by the “back flow” of menstrual blood, rich in endometrial cells, into the pelvic cavity during menses. The immune system destroys the majority of endometriosis but some may still penetrate the body’s defenses. If the immune system is weakened, or does not recognize endometriosis, it can proliferate.

Women whose mother’s had endometriosis are more likely to have endometriosis lending support to a genetic link.

Endometriosis symptoms can include pain during menstruation or throughout the menstrual cycle, painful urination or bowel movements, and/or painful intercourse. When endometriosis damages the reproductive organs, it can lead to infertility.

Endometrial growth is stimulated during the menstrual cycle. Likewise when endometriosis cells attach to an organ, estrogen continues to stimulate their growth. One treatment for endometriosis is to lower the levels of estrogen by using a drug like Lupron thus “starving” the endometriosis of estrogen. Laparoscopic surgery is sometimes necessary to completely remove the implants, cut scar tissue and separate pelvic organs.

Laparoscopic surgery for infertility should ideally be performed by a reproductive endocrinology and infertility specialist. Infertility specialists undergo advanced training in laparoscopic surgery and have extensive experience operating on delicate reproductive organs. They understand if the organs are likely to work normally after performing surgery, and can identify situations necessitating in vitro fertilization.

Male Factor Infertility

Male infertility is common, being present in up to half of all infertile couples. Infertility is certainly not just a “female problem” rather it is a "couples” problem. Fertility in men appears to decline with age, but the effects of age are not as distinct compared to menopause in women. With age, there are declines in the quality and quantity of sperm. The semen analysis is the cornerstone male infertility test and must be completed before any female treatment begins. Learn more about male infertility and treatment.

Ovarian Factor Infertility

Ovarian factor relates to the viability of the eggs within the ovaries. Low ovarian reserve, usually evidenced by abnormally high FSH levels, means that the eggs are declining in quantity and perhaps also in quality, and will not fertilize and develop as readily as normal eggs. When ovarian failure occurs, the eggs have almost completely disappeared. The best reproductive option for women with ovarian failure is to use donor eggs.

Ovulation is controlled by a series of hormonal events occurring each month during the ovulation cycle. During the first part of the ovulation cycle, the hypothalamus releases “gonadotropin releasing hormone” or GnRH which causes the production of follicle stimulating hormone (FSH) and luteinizing hormone (LH) by the pituitary. FSH is responsible for follicular growth and the development of the eggs during the ovulation cycle. LH supports the theca cells in the ovaries that provide androgens and hormonal precursors for the production of estrogen.

Successful ovulation requires that he hypothalamus monitor levels of FSH, LH, and estrogen. The hypothalamus performs its reproductive functions by signaling the pituitary gland to increase or decrease production of these hormones. For example, the hypothalamus registers increasing estrogen levels during early egg development. As healthy follicles develop, they produce increasing amounts of estrogen, which signals a decline in FSH production. Ovulation requires precise control of these reproductive hormones by the hypothalamus.

Once the eggs mature and are ready for ovulation, the hypothalamus signals the pituitary to release a surge of LH, which finally prepares the eggs and causes ovulation 36-38 hours later. Ovulation induction patients receive an injection of hCG, which mimics the LH surge. This is necessary because these patients receive fertility drugs that block spontaneous ovulation.

The follicular structure remaining after ovulation is termed the “corpus luteum”. It produces progesterone which is needed for proper endometrial support and development. The endometrium (uterine lining) must thicken and become more vascular to support the developing embryo. The pre-embryo implants into the endometrium and grows with subsequent fetal development and formation of the placenta. The placenta then produces progesterone which supports the pregnancy.

Ovulatory disorders can be caused by conditions such as polycystic ovarian syndrome (PCOS). In PCOS patients, the androgen levels (male hormones) are too high and thus interfere with the ovulatory cycle. Increased androgens are due to abnormally high insulin levels (hyperinsulenemia), and PCOS can sometimes be treated by lowering insulin levels with drugs like Metformin (glucophage). Once the androgen excess is corrected, spontaneous ovulation will often resume. Some patients lose weight with Metformin, which also helps with ovulation.

Ovulation disorders can be caused by elevated prolactin levels (hyperprolactenemia). Prolactin is the hormone responsible for breast milk production, and levels normally rise after conception. Elevated prolactin levels in the absence of pregnancy can cause ovulatory irregularities. Elevated prolactin levels are sometimes due to a small nonmalignant tumor on the pituitary, which can be removed surgically or treated with medication such as bromocriptine or cabergoline.


Ovarian factor occurs when the ovaries do not contain enough quality eggs. Women are born with a lifetime’s supply of eggs and one/two is ovulated each month in the normal menstrual cycle. Unfortunately, as women age so do their eggs and quality declines until the menopause when eggs lose their ability to fertilize.

Sometimes egg quality declines earlier in life, a condition sometimes termed diminished ovarian reserve or ovarian failure. The reason(s) for this decline are unknown but probably have a genetic basis. One of the first signs of diminishing egg quality is an abnormally elevated day 3 FSH hormone level. Estrogen levels don't increase and FSH production continues. Diminished ovarian reserve is followed by ovarian failure.

Ovarian failure means a woman will have to use an egg donor to have a child. Egg donors are young, healthy females who agree to let another woman use her eggs in an IVF cycle. The donor's eggs are combined with the partner’s sperm, meaning the child will have the genetic makeup of the father and the donor.

Donor egg is also a wonderful option for women who were born without ovaries or who lost ovarian function due to disease or cancer chemotherapy and/or radiation or surgery. These women can still produce healthy children using a donor's eggs and a partner's sperm. Please see our donor egg Web pages for more information.

Fortunately, success rates for donor egg IVF cycles are high and women can have healthy children well into their late forties.


Polycystic Ovarian Syndrome (PCOS)

Polycystic ovarian syndrome was described about a century ago by doctors Stein and Leventhal. PCOS is a common cause of female infertility and usually presents with symptoms of obesity, and extra hair growth, especially on the face, neck and abdomen. We now know that PCOS affects a wide range of women of all weights and is typically defined by elevated androgen hormones (male hormones), the presence of irregular menstrual cycles, extra hair growth, and ovaries covered with cysts seen on ultrasound.

Polycystic ovarian syndrome was described about a century ago by doctors Stein and Leventhal. PCOS is a common cause of female infertility and usually presents with symptoms of obesity, and extra hair growth, especially on the face, neck and abdomen. We now know that PCOS affects a wide range of women of all weights and is typically defined by elevated androgen hormones (male hormones), the presence of irregular menstrual cycles, extra hair growth, and ovaries covered with cysts seen on ultrasound.

The exact cause of PCOS is still unknown. It affects the ovaries, the adrenal glands, the pancreas, the skin, and the brain among other organs. We do know some of the laboratory findings that accompany PCOS including an elevated testosterone level that is above the normal female range though far lower than the normal male range.

PCOS can lead to an increased risk of diabetes, pre-diabetes, or diabetes in pregnancy. Women with PCOS tend to be overweight for unknown reasons. They may have a desire to eat more, or utilize the food they eat for more efficiently (extracting more energy) than non PCOS women who eat the same amount of food. Nevertheless, PCOS patients often struggle to maintain a normal body mass index (BMI). Patients tend to have the accumulated fat on their waist as apposed to their hips, with an increased waist to hip ratio. This is sometimes referred to as a “pear shaped” body appearance.

PCOS is effectively treated with birth control pills in women who do not wish to conceive. BCP’s prevent the extra hair growth in several different ways, preventing excessive testosterone production, increasing testosterone binding, and possibly by acting at the hair follicle to slow growth. When PCOS is accompanied by pre-diabetes, or when weight loss is desired, metformin, a medicine that has traditionally used to treat diabetes, may be used. Metformin lowers circulating insulin levels which are elevated in PCOS patients (hyperinsulenemia).

When the main symptom of PCOS is infertility, medicines to help regulate ovulation are used like Clomid, FSH or Letrozole. Metformin is also being used as a first line treatment for PCOS.

PCOS patients tend to make a lot of eggs when using ovulation inducing drugs, so they have an increased risk of multiple pregnancies. These drugs are best prescribed by physicians experienced in their use such as an infertility specialist/reproductive endocrinologist. Medical treatment is often combined with intrauterine insemination. (See ovulation induction section)



Tubal Disease

The fallopian tubes "carry" the eggs from the ovaries to the uterus, with fertilization occurring along the way. Sometimes the tubes become partially or fully obstructed due to conditions such as endometriosis. Endometrial implants can attach to, penetrate and scar the fallopian tubes, making egg transport difficult or impossible.

Tubal health is determined using the hysterosalpingogram test (HSG). Radiopaque dye is injected into the uterus and its flow through the uterus and tubes is monitored via sequential x-rays. Tubal obstructions show up as a concentration of dye behind the blockage.

Some women have their tubes "tied" (tuballigation) as a birth control method, and later decide to have children and seek tubal reversal surgery. The decision is usually due to changes in life situations such as divorce and remarriage. While the tubes can sometimes be reconnected surgically and IVF is often effective, tubal ligation should be considered a permanent means of birth control.

Uterine Disease

The uterus must be normally shaped and free of obstructions to support a developing fetus. Large fibroids or polyps can make implantation and fetal development difficult. Your physician will investigate the uterine cavity using ultrasound techniques or hysterosalpingogram to be sure that fibroids and polyps are not present.

Some women are born with a uterine structural abnormality such as a bicornuate uterus (two horned). A bicornuate uterus does not cause infertility but it does increase the chances of miscarriage and can cause problems during pregnancy. A septate uterus is another example of a structural abnormality causing repeat pregnancy loss. Pelvic inflammatory disease, usually caused by infection, can damage the uterus by causing scar tissue within or outside of the uterus. Polyps and fibroids can often be removed, and some structural abnormalities, such as septate uterus can be corrected surgically.

As long as a woman's uterus is normal she can carry children even after the menopause using embryos from a donor egg IVF cycle.

Unexplained Infertility

Sometimes no cause for a couple's infertility can be identified. Treatment depends upon many factors such as female age, previous treatment history, etc.