What causes infertility in women?
Women need functioning ovaries, fallopian tubes, and a uterus to get pregnant. Conditions affecting any one of these organs can contribute to female infertility. Some of these conditions are listed below and can be evaluated using a number of different tests.
Disruption of ovarian function (presence or absence of ovulation (anovulation) and effects of ovarian “age”)
A woman’s menstrual cycle is, on average, 28 days long. Day 1 is defined as the first day of “full flow.” Regular predictable periods that occur every 24 to 32 days likely reflect ovulation. A woman with irregular periods is likely not ovulating.
Ovulation can be predicted by using an ovulation predictor kit and can be confirmed by a blood test to check the woman’s progesterone level on day 21 of her menstrual cycle. Although several tests exist to evaluate a woman’s ovarian function, no single test is a perfect predictor of fertility. The most commonly used markers of ovarian function include follicle stimulating hormone (FSH) value on day 3 to 5 of the menstrual cycle, anti-müllerian hormone value (AMH), and antral follicle count (AFC) using a transvaginal ultrasound.
Disruptions in ovarian function may be caused by several conditions and warrants an evaluation by a doctor.
When a woman doesn’t ovulate during a menstrual cycle, it’s called anovulation. Potential causes of anovulation include the following
- Polycystic ovary syndrome (PCOS). PCOS is a condition that causes women to not ovulate, or to ovulate irregularly. Some women with PCOS have elevated levels of testosterone, which can cause acne and excess hair growth. PCOS is the most common cause of female infertility.
- Diminished ovarian reserve (DOR). Women are born with all of the eggs that they will ever have, and a woman’s egg count decreases over time. Diminished ovarian reserve is a condition in which there are fewer eggs remaining in the ovaries than normal. The number of eggs a woman has declines naturally as a woman ages. It may also occur due to congenital, medical, surgical, or unexplained causes. Women with diminished ovarian reserve may be able to conceive naturally, but will produce fewer eggs in response to fertility treatments.
- Functional hypothalamic amenorrhea (FHA). FHA is a condition caused by excessive exercise, stress, or low body weight. It is sometimes associated with eating disorders such as anorexia.
- Improper function of the hypothalamus and pituitary glands. The hypothalamus and pituitary glands in the brain produce hormones that maintain normal ovarian function. Production of too much of the hormone prolactin by the pituitary gland (often as the result of a benign pituitary gland tumor), or improper function of the hypothalamus or pituitary gland, may cause a woman not to ovulate.
- Premature ovarian insufficiency (POI). POI, sometimes referred to as premature menopause, occurs when a woman’s ovaries fail before she is 40 years of age. Although certain exposures, such as chemotherapy or pelvic radiation therapy, and certain medical conditions may cause POI, the cause is often unexplained. About 5% to 10% of women with POI conceive naturally and have a normal pregnancy.
- Menopause. Menopause is an age-appropriate decline in ovarian function that usually occurs around age 50. By definition, a woman in menopause has not had a period in one year. She may experience hot flashes, mood changes, difficulty sleeping, and other symptoms as well.
Fallopian tube obstruction (whether fallopian tubes are open, blocked, or swollen)
Risk factors for blocked fallopian tubes (tubal occlusion) can include a history of pelvic infection, history of ruptured appendicitis, history of gonorrhea or chlamydia, known endometriosis, or a history of abdominal surgery.
Tubal evaluation may be performed using an X-ray that is called a hysterosalpingogram (HSG), or by chromopertubation (CP) in the operating room at time of laparoscopy, a surgical procedure in which a small incision is made and a viewing tube called a laparoscope is inserted.
- Hysterosalpingogram (HSG) is an X-ray of the uterus and fallopian tubes. A radiologist injects dye into the uterus through the cervix and simultaneously takes X-ray pictures to see if the dye moves freely through fallopian tubes. This helps evaluate tubal caliber (diameter) and patency.
- Chromopertubation is similar to an HSG but is done in the operating room at the time of a laparoscopy. Blue-colored dye is passed through the cervix into the uterus and spillage and tubal caliber (shape) is evaluated.
Abnormal uterine contour (physical characteristics of the uterus)
Depending on a woman’s symptoms, the uterus may be evaluated by transvaginal ultrasound to look for fibroids or other anatomic abnormalities. If suspicion exists that the fibroids may be entering the endometrial cavity, a sonohystogram (SHG) or hysteroscopy (HSC) may be performed to further evaluate the uterine environment.