Facts you should know about infertility
*Infertility facts medically edited by: Charles Patrick Davis, MD, PhD
Sperm and egg fertilization process
- Infertility means not being able to become pregnant within certain parameters.
- Infertility is a common problem of about 6% of women aged 15 to 44.
- Infertility can be due to the woman, the man, both sexes, or unknown problems.
- Infertility in men can be due to varicocele, trauma, low or absent sperm count, sperm damage, alcohol use, or certain diseases like diabetes, cystic fibrosis, autoimmune diseases, infections, hormonal disorders, and genetic disorders.
- Risk factors for men's infertility include alcohol and drug use, toxins, smoking, age, health problems like obesity, medicines like testosterone, radiation, excessive testicular heat, and chemotherapy.
- Risk factors for women's infertility include ovulation problems like polycystic ovary syndrome , blocked fallopian tubes, uterine problems, uterine fibroids, age, stress, poor diet, athletic training, and those risk factors listed for men.
- Aging is a major risk factor that decreases a woman's fertility. After age 35, about 33% of couples have fertility problems. Older women's eggs are reduced in number, not as healthy, and less likely to be released by the ovary. The woman is also more likely to have a miscarriage and other health problems.
- Women under age 35 should try for a year and women older than 35 should try for 6 months to become pregnant before contacting their doctors if they have no health problems.
- Doctors use the histories of both partners and may run tests such as sperm studies, ovulation tests, ultrasound, hysterosalpingography, or laparoscopy.
- Infertility may be treated with medicine, surgery, artificial insemination, or assisted reproductive technology, based on the couple’s test results and other factors.
- Multiple medicines may be used to treat infertility in women.
- Intrauterine insemination is artificial insemination in which a woman is injected with sperm into the uterus.
- In assisted reproductive technology (ART), a woman’s eggs are removed and mixed with sperm to make embryos that are placed back in the woman's body. Depending on the woman's age, ART has about a 3% to 31% success rate.
- There are several types of ART: in vitro fertilization, zygote transfer, gamete transfer, and intracytoplasmic sperm injection.
- Some couples obtain a baby with donor eggs when the woman's male partner’s sperm is used to fertilize another woman’s egg, and that other woman carries the fetus to term, and the infant is adopted.
- A gestational carrier is a woman who has an embryo placed in her uterus, carries the fetus to term and gives the baby to the couple (or responsible persons) that produced the embryo.
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Infertility treatment can be physically uncomfortable, time-consuming,
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What is infertility?
In general, infertility is defined as not being able to get pregnant (conceive) after one year (or longer) of unprotected sex. Because fertility in women is known to decline steadily with age, some providers evaluate and treat women aged 35 years or older after 6 months of unprotected sex. Women with infertility should consider making an appointment with a reproductive endocrinologist -- a doctor who specializes in managing infertility. Reproductive endocrinologists may also be able to help women with recurrent pregnancy loss, defined as having two or more spontaneous miscarriages.
Pregnancy is the result of a process that has many steps.
To get pregnant
- A woman’s body must release an egg from one of her ovaries.
- A man’s sperm must join with the egg along the way (fertilize).
- The fertilized egg must go through a fallopian tube toward the uterus (womb).
- The embryo must attach to the inside of the uterus (implantation).
Infertility may result from a problem with any or several of these steps.
Impaired fecundity is a condition related to infertility and refers to women who have difficulty getting pregnant or carrying a pregnancy to term.
Is infertility a common problem?
Yes. About 6% of married women aged 15 to 44 years in the United States are unable to get pregnant after one year of trying (infertility). Also, about 12% of women aged 15 to 44 years in the United States have difficulty getting pregnant or carrying a pregnancy to term (impaired fecundity).
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Is infertility just a woman's problem?
No, infertility is not always a woman’s problem. Both men and women can contribute to infertility.
Many couples struggle with infertility and seek help to become pregnant, but it is often thought of as only a woman’s condition. However, in about 35% of couples with infertility, a male factor is identified along with a female factor. In about 8% of couples with infertility, a male factor is the only identifiable cause.
Almost 9% of men aged 25 to 44 years in the United States reported that they or their partner saw a doctor for advice, testing, or treatment for infertility during their lifetime.
What causes infertility in men?
Infertility in men can be caused by different factors and is typically evaluated by a semen analysis. When a semen analysis is performed, the number of sperm (concentration), motility (movement), and morphology (shape) are assessed by a specialist. A slightly abnormal semen analysis does not mean that a man is necessarily infertile. Instead, a semen analysis helps determine if and how male factors are contributing to infertility.
Disruption of testicular or ejaculatory function
- Varicoceles, a condition in which the veins on a man’s testicles are large and cause them to overheat. The heat may affect the number or shape of the sperm.
- Trauma to the testes may affect sperm production and result in lower number of sperm.
- Unhealthy habits such as heavy alcohol use, smoking, anabolic steroid use, and illicit drug use.
- Use of certain medications and supplements.
- Cancer treatment involving the use of certain types of chemotherapy, radiation, or surgery to remove one or both testicles
- Medical conditions such as diabetes, cystic fibrosis, certain types of autoimmune disorders, and certain types of infections may cause testicular failure.
- Improper function of the hypothalamus or pituitary glands. The hypothalamus and pituitary glands in the brain produce hormones that maintain normal testicular function. Production of too much prolactin, a hormone made by the pituitary gland (often due to the presence of a benign pituitary gland tumor), or other conditions that damage or impair the function of the hypothalamus or the pituitary gland may result in low or no sperm production.
- These conditions may include benign and malignant (cancerous) pituitary tumors, congenital adrenal hyperplasia, exposure to too much estrogen, exposure to too much testosterone, Cushing’s syndrome, and chronic use of medications called glucocorticoids.
- Genetic conditions such as a Klinefelter’s syndrome, Y-chromosome microdeletion, myotonic dystrophy, and other, less common genetic disorders may cause no sperm to be produced, or low numbers of sperm to be produced.
What increases a man's risk of infertility?
- Age. Although advanced age plays a much more important role in predicting female infertility, couples in which the male partner is 40 years old or older are more likely to report difficulty conceiving.
- Being overweight or obese.
- Excessive alcohol use.
- Use of marijuana.
- Exposure to testosterone. This may occur when a doctor prescribes testosterone injections, implants, or topical gel for low testosterone, or when a man takes testosterone or similar medications illicitly for the purposes of increasing their muscle mass.
- Exposure to radiation.
- Frequent exposure of the testes to high temperatures, such as that which may occur in men confined to a wheelchair, or through frequent sauna or hot tub use.
- Exposure to certain medications such as flutamide, cyproterone, bicalutamide, spironolactone, ketoconazole, or cimetidine.
- Exposure to environmental toxins including exposure to pesticides, lead, cadmium, or mercury.
Men and women are equally likely to have fertility problems.
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 for at least 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.
Fallopian tubes may be evaluated by hysterosalpingogram (HSG) or by chromopertubation (CP).
- 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 uterusexternal icon may be evaluated by transvaginal ultrasound to look for fibroidsexternal icon 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.
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What increases a woman's risk of infertility?
Female fertility is known to decline with
- Age. About 1 in 6 couples in which the woman is 35 and older have fertility problems. Aging decreases fertility because older women have fewer eggs left, the eggs are less healthy, and the woman is more likely to have health conditions that can cause fertility problems. Aging also increases a woman’s chances of miscarriage and of having a child with a genetic abnormality.
- Excessive alcohol use.
- Extreme weight gain or loss.
- Excessive physical or emotional stress that results in amenorrhea (absent periods).
How long should couples try to get pregnant before seeing a doctor?
Most experts suggest women younger than age 35 with no apparent health or fertility problems try to conceive for at least one year before seeing a doctor. However, for women aged 35 years or older, couples should see a health care provider after 6 months of trying unsuccessfully. A woman’s chances of having a baby decrease rapidly every year after the age of 30.
Some health problems also increase the risk of infertility. So, couples with the following signs or symptoms should not delay seeing their health care provider when they are trying to become pregnant:
- Irregular periods or no menstrual periods.
- Very painful periods.
- Pelvic inflammatory disease.
- More than one miscarriage.
- Suspected male factor (i.e., history of testicular trauma, hernia surgery, chemotherapy, or infertility with another partner).
It is a good idea for any woman and her partner to talk to a health care provider before trying to get pregnant. They can help you get your body ready for a healthy baby, and can also answer questions on fertility and give tips on conceiving.
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How will doctors find out if a woman and her partner have fertility problems?
Doctors will begin by collecting a medical and sexual history from both partners. The initial evaluation usually includes a semen analysis, a tubal evaluation, and ovarian reserve testing.
How do doctors treat infertility?
Infertility can be treated with medicine, surgery, intrauterine insemination, or assisted reproductive technology.
Often, medication and intrauterine insemination are used at the same time. Doctors recommend specific treatments for infertility on the basis of
- The factors contributing to the infertility.
- The duration of the infertility.
- The age of the female.
- The couple’s treatment preference after counseling about success rates, risks, and benefits of each treatment option.
What are some of the specific treatments for male infertility?
Male infertility may be treated with medical, surgical, or assisted reproductive therapies depending on the underlying cause. Medical and surgical therapies are usually managed by an urologist who specializes in infertility. A reproductive endocrinologist may offer intrauterine inseminations (IUIs) or in vitro fertilization (IVF) to help overcome male factor infertility.
What medicines are used to treat infertility in women?
Some common medicines used to treat infertility in women include
- Clomiphene citrate (Clomid®*) is a medicine that causes ovulation by acting on the pituitary gland. It is often used in women who have polycystic ovary syndrome (PCOS)external icon or other problems with ovulation. It is also used in women with normal ovulation to increase the number of mature eggs produced. This medicine is taken by mouth.
- Letrozole (Femara ®*) is a medication that is frequently used off-label to cause ovulation. It works by temporarily lowering a woman’s progesterone level, which causes the brain to naturally make more FSH. It is often used to induce ovulation in woman with PCOS, and in women with normal ovulation to increase the number of mature eggs produced in the ovaries. It is taken by mouth.
- Human menopausal gonadotropin or hMG (Menopur®*; Repronex®*; Pergonal®*) is an injectable medication often used for women who don’t ovulate because of problems with their pituitary gland -- hMG acts directly on the ovaries to stimulate development of mature eggs.
- Follicle-stimulating hormone or FSH (Gonal-F®*; Follistim®*) is an injectable medication that works much like hMG. It stimulates development of mature eggs within the ovaries.
- Gonadotropin-releasing hormone (GnRH) analogs and GnRH antagonists are medications that act on the pituitary gland to prevent a woman from ovulating. They are used during in vitro fertilization cycles, or to help prepare a woman’s uterus for an embryo transfer. These medications are usually injected or given with a nasal spray.
- Metformin (Glucophage®*) is a medicine doctors use for women who have insulin resistance or diabetes and PCOSexternal icon. This drug helps lower the high levels of male hormones in women with these conditions. This helps the body to ovulate. Sometimes clomiphene citrate or FSH is combined with metformin. This medicine is taken by mouth.
- Bromocriptine (Parlodel®*) and Cabergoline (Dostinex ®*) are medications used for women with ovulation problems because of high levels of prolactin. These medications are taken by mouth.
*Note: Use of trade names and commercial sources is for identification only and does not imply endorsement by the US. Department of Health and Human Services.
Many fertility drugs increase a woman’s chance of having twins, triplets, or other multiples. Women who are pregnant with multiple fetuses may have more problems during pregnancy. Multiple fetuses have a higher risk of being born prematurely (too early). Premature babies are at a higher risk of health and developmental problems.
What is intrauterine insemination (IUI)?
Intrauterine insemination (IUI) is an infertility treatment that is often called artificial insemination. In this procedure, specially prepared sperm are inserted into the woman’s uterus. Sometimes the woman is also treated with medicines that stimulate ovulation before IUI.
IUI is often used to treat
- Mild male factor infertility.
- Couples with unexplained infertility.
What is assisted reproductive technology (ART)?
Assisted Reproductive Technology (ART) includes all fertility treatments in which either eggs or embryos are handled outside of the body. In general, ART procedures involve removing mature eggs from a woman’s ovaries using a needle, combining the eggs with sperm in the laboratory, and returning the embryos to the woman’s body or donating them to another woman. The main type of ART is in vitro fertilization (IVF).
How often is assisted reproductive technology (ART) successful?
Success rates vary and depend on many factors, including the clinic performing the procedure, the infertility diagnosis, and the age of the woman undergoing the procedure. This last factor -- the woman’s age -- is especially important.
ART can be expensive and time-consuming, but it has allowed many couples to have children that otherwise would not have been conceived. The most common complication of ART is a multiple pregnancy. This is a problem that can be prevented or minimized by limiting the number of embryos that are transferred back to the uterus. For example, transfer of a single embryo, rather than multiple embryos, greatly reduces the chances of a multiple pregnancy and its risks such as preterm birth.
What are the different types of assisted reproductive technology (ART)?
In vitro fertilization (IVF), meaning fertilization outside of the body, is the most common form of ART. Eggs and sperm are combined in a laboratory to create embryos. After about three to five days, the embryo (or embryos) is transferred into the woman’s uterus. Embryos can also be frozen for a future transfer. When a frozen embryo is thawed and transferred into a woman’s uterus it is called a frozen embryo transfer (FET).
Intracytoplasmic sperm injection (ICSI) is a type of IVF that is often used for couples with male factor infertility. With ICSI, a single sperm is injected into a mature egg. The alternative to ICSI is “conventional” fertilization where the egg and many sperm are placed in a petri dish together and the sperm fertilizes an egg on its own.
- Zygote intrafallopian transfer (ZIFT) or tubal embryo transfer and gamete intrafallopian transfer (GIFT) are other ART methods that are rarely used in the United States today. With ZIFT, fertilization occurs in the laboratory similar to IVF. Then the very young embryo is transferred to the fallopian tube instead of the uterus. GIFT involves transferring eggs and sperm into the woman’s fallopian tube and fertilization occurs in the woman’s body.
ART procedures sometimes involve the use of donor eggs (eggs from another woman), donor sperm, or donated embryos. Donor eggs are sometimes used for women who cannot produce eggs. Also, donor eggs or donor sperm are sometimes used when the woman or man has a genetic disease that can be passed on to the baby. An infertile woman or couple may also use donor embryos. These are embryos that were either created by couples in infertility treatment or were created from donor sperm and donor eggs. The donated embryo is transferred to the uterus. The child will not be genetically related to either parent.
Women with ovaries but no uterus may be able to use a gestational carrier. This may also be an option for women who shouldn’t become pregnant because of a serious health problem. In this case, a woman uses her own egg. It is fertilized by her partner’s sperm and the embryo is placed inside the carrier’s uterus.
What is preimplantation genetic testing (PGT)?
Preimplantation genetic testing is a procedure used to identify genetic disorders or chromosomal abnormalities in embryos created during an IVF cycle. One or more cells are biopsied from each embryo and sent for testing. These procedures used to be referred to as preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD).
Medically Reviewed on 4/13/2021
United States. Centers for Disease Control and Prevention (CDC). Division of Reproductive Health. National Center for Chronic Disease Prevention and Health Promotion. "Infertility FAQs." Apr. 13, 2021. <http://www.cdc.gov/reproductivehealth/infertility/>.