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Causes of Infertility

Listed below are some common causes of infertility.

Ovulation Dysfunction

Causes of Infertility explainedProblems with ovulation account for 40% of infertility in women and result in the ovary’s inability to release an egg. Irregular, infrequent or absent menstrual cycles are classic symptoms of ovulation disorders. The vast majority of the time, this is caused by a hormonal imbalance from improper coordination and communication between the hypothalamus and the pituitary gland in the brain. Together these two release hormones that regulate and stimulate the ovaries to develop eggs each month. If the communication is not precise then ovulation does not occur. PCOS (Polycystic Ovarian Syndrome) is an example of this miscommunication where many follicles grow and develop into small cysts that never release an egg because of a lack of FSH (Follicle Stimulating Hormone) from the pituitary gland. Abnormal ovulation may also be associated with extremely low body weight or with being over weight, as well as any significant recent change in weight (loss or gain).


A woman is at her most fertile between the ages of 15 and 24, after which fertility potential begins to gradually decline. By the mid-30’s about 1/3 of women who delayed having children will have a problem becoming pregnant, and for women over 40, at least ½ will have difficulty conceiving. In addition to declining fertility (number of available eggs), the quality of the available eggs is also compromised as a woman ages. Older eggs are less likely to fertilize and develop normally with a resulting increase in the miscarriage and chromosome abnormality rates.

Damaged Fallopian Tubes

Damaged or blocked fallopian tubes are a frequent cause of infertility. Tubal damage can be caused by a past infection, such as sexually transmitted infection (STI), or a previous abdominal operation. When the fallopian tubes are obstructed the sperm and the egg cannot meet to fertilize. In addition, when the blocked fallopian tubes are filled with fluid (hydrosalpinx), this fluid can negatively affect the development of an embryo placed in the uterus during In Vitro Fertilization (IVF). As a result, it is recommended that the hydrosalpinx be removed before patients proceed with an IVF cycle. Surgical repair of damaged fallopian tubes is possible, but pregnancy results are much lower than with IVF and a higher ectopic (tubal) pregnancy rate is seen than with IVF.

Male Factor

A semen analysis is the primary test used to identify if there are abnormalities in the sperm that may affect fertility. The semen analysis may reveal no sperm or a low concentration, abnormalities of sperm movement (motility), and/or abnormalities of sperm shape (morphology). Difficulties achieving a pregnancy are linked to a male factor alone in 30% of couples and, is combined with female factors in an additional 30% of couples. Therefore, male factor contributes in over half of all couples having trouble conceiving.

Male infertility can be due to a variety of conditions. Some of these conditions are reversible, such as an obstruction, an anatomic abnormality such as varicocele, or a hormonal deficiency. Other conditions are not reversible, such as severe damage to the testicles caused by a previous infection (i.e. mumps). Additionally, environmental factors, medications (blood pressure, testosterone, and nutritional supplements that mimic testosterone), and habits (alcohol, and recreational drug use) can adversely affect sperm quality and function. Some men may have an underlying genetic issue causing the infertility. Several treatment options are available including medical therapies and use of low and high tech laboratory procedures.


Every month the lining of the uterus (endometrium) thickens in preparation for the implantation of an embryo. If a pregnancy doesn't occur then the lining is shed during menstruation. On occasion, during menstruation some of these endometrial cells flow back through the fallopian tubes and into the pelvis instead of out of the body (retrograde menstruation). These displaced cells may attach to the ovaries and other pelvic organs creating islands of endometrium outside the uterus. Each month these cells respond to the monthly hormones and thicken and bleed causing irritation and scarring in the pelvis that may lead to pain and infertility. Additionally, chemicals released from this displaced endometrial tissue can be toxic to ovulated (just released) eggs, bathing them before the eggs enter the fallopian tubes. Symptoms of endometriosis may include painful menstrual periods, painful intercourse, and pelvic pain. There is no correlation between the severity of the symptoms and the extent of the disease. Sometimes there are no symptoms at all. Several forms of treatment are available, including medical therapy, surgery, and IVF if the endometriosis is moderate to severe.


Body weight plays a critical role in reproduction for both men and women as an excess or deficiency in body fat can lead to reproductive failure. The effects of body fat and fertility are well known for women and not yet well studied in men. Infertility affects both overweight and underweight women about equally. Because of the interaction of hormones and fat cells, obese women progressively increase their estrogen hormone levels until ovulation ceases and they become infertile. Slender women progressively decrease their estrogen levels until the reproductive cycle is “turned off”. Ironically, both thin and obese women develop irregular reproductive cycles, but by different means. The good news is that more than 70% of women who are infertile because of body weight excess or deficiency will conceive spontaneously if their weight is corrected through weight reduction or weight gain as appropriate. Many underweight women find the challenge of gaining weight just as daunting as an overweight woman finds in losing weight. Slender women who diet strenuously or exercise vigorously often find it hard to accept that their “healthful lifestyle” contributes to their infertility. Once the association of low body weight and infertility is made, implementation of a weight gain program comes more easily. Overweight women and couples for whom weight reduction is recommended often view this recommendation as another wasted effort since past attempts to diet or exercise have not been successful. Yet with education, understanding, and encouragement for each weight loss accomplishment, the steady loss of a pound per week will maintain realistic expectations and help prevent abandonment of the weight loss program. For some women, losing only 10% of their weight is needed for spontaneous ovulation to occur and additional infertility treatment may not be needed.

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