Possible causes of infertility in males include a low sperm count and taking certain medications. Possible causes of infertility in females include ovulation disorders and endometriosis.

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Infertility is when a male or female cannot conceive due to a problem with the reproductive system of either partner.

Infertility can be primary or secondary. Primary infertility is when someone is not able to conceive at all. Secondary infertility is when someone has previously conceived but is no longer able to.

This article explains infertility’s causes, types, and treatment, as well as other things a person may wish to know about infertility in both sexes.

Infertility is defined as the inability to get pregnant after 12 months of trying. Any person of either sex who fits this definition is experiencing infertility.

Causes in males

The following are common causes of infertility in males:

Problems with semen and sperm

Semen is the milky fluid that the penis releases during ejaculation and consists of fluid and sperm. The fluid comes from the prostate gland, the seminal vesicle, and other sex glands. The sperm is produced in the testicles. When the ejaculate comes out of the penis, semen helps transport the sperm toward the egg.

Things that can make it more difficult for sperm to fertilize the egg include having a sperm count below 15 million, low sperm motility, or sperm that have an unusual shape and a harder time fertilizing the egg.

About 2% of males may have these types of issues with their sperm. They can result from:

  • A medical condition: This could be a testicular infection, cancer, or a surgery.
  • Overheated testicles: Causes include an undescended testicle, a varicocele, a varicose vein in the scrotum, the use of saunas or hot tubs, wearing tight clothes, and working in hot environments.
  • Ejaculation disorders: If the ejaculatory ducts are blocked, semen may be ejaculated into the bladder.
  • Hormonal imbalance: Hypogonadism, for example, can lead to a testosterone deficiency.

Other causes

Other causes may include:

  • Genetic factors: A male should have an X and Y chromosome. If a person has two X chromosomes and one Y chromosome, as in Klinefelter syndrome, the testicles will develop abnormally, and there will be low testosterone and a low sperm count or no sperm.
  • Mumps: If this occurs after puberty, inflammation of the testicles may affect sperm production.
  • Hypospadias: With this congenital anomaly, the urethral opening is under the penis instead of at its tip. Doctors usually surgically correct this condition during infancy. If the correction is not done, it may be harder for the sperm to reach the female’s cervix. Hypospadias affects about 1 in every 200 newborn boys in the United States.
  • Cystic fibrosis: This is a chronic disease that results in the creation of sticky mucus. This mucus mainly affects the lungs, but males may also have an absent vas deferens. The vas deferens carries sperm from the epididymis to the ejaculatory duct and the urethra.
  • Radiation therapy or chemotherapy: These treatments can both impair sperm production. In the case of radiation therapy, the severity usually depends on how near to the testicles the radiation occurred.
  • Other diseases: Conditions that are sometimes linked to lower fertility in males are anemia, Cushing’s syndrome, diabetes, and thyroid disease.
  • Medications: Some medications increase the risk of fertility problems in males. These include sulfasalazine (Azulfidine) and anabolic steroids.

Causes in females

Infertility in females can also have a range of causes.

Problems with ovulation

Ovulation disorders make up about 25% of infertility cases in females. Ovulation is the monthly release of an egg. The eggs may never be released, or they may only be released in some cycles.

Ovulation disorders can occur due to:

  • Hyperprolactinemia: If prolactin levels are high and the female is not pregnant or breastfeeding, it may affect ovulation and fertility.
  • Thyroid problems: An overactive or underactive thyroid gland can lead to a hormonal imbalance that interferes with ovulation.
  • Polycystic ovary syndrome (PCOS): This is a hormonal condition that can cause frequent or prolonged menstruation and can interfere with ovulation.

Problems in the uterus or fallopian tubes can also prevent the egg from traveling from the ovary to the uterus, or womb. If the egg does not travel, it can be harder to conceive naturally.

Other causes

Other causes include:

  • Chronic conditions: These include AIDS or cancer.
  • Primary ovarian insufficiency (POI): The ovaries stop working normally before the age of 40 years.
  • Poor egg quality: The quality of the eggs may interfere with conception. As a female ages, the number and quality of the eggs declines. Eggs that are damaged or develop genetic abnormalities may also not be able to sustain a pregnancy. The older a female is, the higher the risk.
  • Surgery: Pelvic surgery can sometimes cause scarring or damage to the fallopian tubes. Cervical surgery can sometimes cause scarring or shortening of the cervix. The cervix is the neck of the uterus.
  • Submucosal fibroids: Benign or noncancerous tumors occur in the muscular wall of the uterus. They can interfere with implantation or block the fallopian tube, preventing sperm from fertilizing the egg.
  • Endometriosis: Cells that normally occur within the lining of the uterus start growing elsewhere in the body.
  • Tubal ligation: In females who have chosen to have their fallopian tubes blocked, the process can be reversed, but the chances of becoming fertile again are not high.

There are certain risk factors that can increase the chance of infertility for both sexes. These include:

  • Smoking: Smoking significantly increases the risk of infertility in both sexes, and it may undermine the effects of fertility treatment. Smoking during pregnancy increases the chance of pregnancy loss. Passive smoking has also been linked to lower fertility.
  • Chemotherapy: Some chemotherapy drugs can result in ovarian failure or significantly reduce sperm count.
  • Radiation: If this is aimed near the reproductive organs, it can increase the risk of fertility problems.
  • Sexually transmitted infections (STIs): Chlamydia can damage the fallopian tubes in a female and cause inflammation in a male’s scrotum. Some other STIs may also cause infertility.
  • Age: The female’s ability to conceive may start to fall gradually before or around the age of 35 years, while male fertility starts to fall after the age of 40 years.

In addition, other factors may also be associated with infertility, though in many cases, the research is still insufficient. These include:

  • Narcotics: Consumption of drugs such as cannabis or cocaine can lower the sperm count. Some females who use cannabis or cocaine may also have fertility problems.
  • Exposure to certain chemicals: Some pesticides, herbicides, metals (such as lead), detergents, and solvents have been linked to fertility problems in both sexes.
  • Obesity: This may reduce the chance of conceiving for both sexes.
  • Stress: Stress can be a factor, especially if it leads to reduced sexual activity. It can also affect female ovulation and male sperm production.
  • Exercise: Too much and too little exercise can lead to fertility problems in both sexes. In males, it can affect the sperm count.
  • Nutrition: An unhealthy diet can impact fertility in males and females. If an eating disorder leads to serious weight loss, fertility problems may also arise.
  • Alcohol misuse: Exessive alcohol consumption may reduce sperm count. It may also interfere with the success of in vitro fertilization (IVF) treatments.

Treatment to help a person conceive naturally will depend on many factors, including the age of the person who wishes to conceive, how long infertility has lasted, personal preferences, and their general state of health.

Frequency of intercourse

The first strategy a couple trying to conceive may wish to try is having sexual intercourse more often around the time of ovulation.

Typically the menstrual cycle lasts for about28–32 days. Counting from the first day of the last period, a female will usually ovulate anywhere between day 11 and day 21.

Any person whose cycle is shorter than 21 days or longer than 35 days should see their doctor for an evaluation.

Learn more about how to calculate an ovulation cycle.

Other treatments

However, timing intercourse may not be sufficient on its own to help a couple conceive. Treatments will depend on the underlying cause of infertility.

In males, this can include medications for erectile dysfunction. Surgery may include a procedure to remove a varicose vein in the scrotum or repair a blocked epididymis.

In females, doctors can prescribe fertility drugs to regulate or induce ovulation. These can include clomiphene (Clomid, Serophene), letrozole (Femara), dopamine agonist medications, and a variety of hormonal drugs.

Learn more about fertility drugs for females.

If the fallopian tubes are blocked or scarred, surgical repair may make it easier for eggs to pass through. A person may also be advised to undergo IVF.

Doctors may also treat endometriosis with laparoscopic surgery. They make a small incision in the abdomen and insert a thin, flexible microscope with a light at the end, called a laparoscope. The surgeon can then remove implants and scar tissue, which may reduce pain and aid fertility.

The following methods are currently available for assisted or artificial conception:

  • Intrauterine insemination (IUI): At the time of ovulation, a doctor inserts a fine catheter through the cervix into the uterus to place a sperm sample directly into the uterus.
  • In vitro fertilization (IVF): Doctors place the sperm with unfertilized eggs in a petri dish, where fertilization can take place. They then place the embryo in the uterus to begin a pregnancy. IVF techniques can include intracytoplasmic sperm injection (ICSI) and assisted hatching.
  • Sperm or egg donation: If necessary, a person can use egg or sperm donation. Fertility treatment with donor eggs can be done using IVF.
  • Electric or vibratory stimulation to achieve ejaculation: It may be possible to help a person achieve ejaculation with electric or vibratory stimulation. This can help a male who cannot ejaculate normally, for example because of a spinal cord injury.
  • Surgical sperm aspiration: The sperm is removed from a part of the male reproductive tract such as the vas deferens, testicle, or epididymis. Doctors will use IVF to fertilize the egg or freeze the sperm for later use.

A person may want to visit a physician if there is no pregnancy after 12 months of trying.

If the female partner is over age 35 years, the couple may wish to see a doctor earlier, as fertility testing can take time. For example, a person over 35 years may want to see a doctor after 6 months, while a person over 40 years may want to see a doctor as soon as they realize they are not becoming pregnant.

A doctor can give advice and carry out some preliminary assessments.

The doctor may ask about a person’s sexual habits and make recommendations regarding these. Tests are available, but testing does not always reveal a specific cause.

Infertility tests for males

The doctor will ask about medical history, medications, and sexual habits and perform a physical examination.

If a test shows an abnormality, the doctor may recommend an examination of the testicles for lumps or deformities and an exam of the shape and structure of the penis.

In addition, the doctor may order the following tests:

  • Semen analysis: A sample may be taken to test for sperm concentration, motility, color, and quality, as well as the presence of blood or infection. Sperm counts can fluctuate, so several samples may be necessary.
  • Blood test: The lab will test for levels of testosterone and other hormones.
  • Ultrasound: This may reveal issues such as ejaculatory duct obstruction or retrograde ejaculation.
  • Chlamydia test: Chlamydia can affect fertility, but antibiotics can treat it. However, antibiotics cannot cure any existing damage to fertility.

Infertility tests for females

A female will undergo a general physical examination, and the doctor will ask about medical history, medications, menstruation cycle, and sexual habits.

They will also undergo a gynecologic examination and a number of tests:

  • Blood test: This can assess hormone levels and whether a female is ovulating.
  • Hysterosalpingography: A technician injects fluid into the uterus and takes X-rays to determine whether the fluid travels properly out of the uterus and into the fallopian tubes. If a blockage is present, surgery may be necessary.
  • Laparoscopy: A thin, flexible tube with a camera at the end is inserted into the abdomen and pelvis, allowing a doctor to look at the fallopian tubes, uterus, and ovaries. This can reveal signs of endometriosis, scarring, blockages, and some irregularities in the uterus and fallopian tubes.

Other tests can include:

  • ovarian reserve testing to count the eggs after ovulation
  • pelvic ultrasound to produce an image of the uterus and ovaries
  • thyroid function test, as this may affect the hormonal balance

For couples who experience fertility problems and those who wish to have children at an older age, there are more options available than ever before.

In 1978, the first baby was born as a result of IVF. Today, about 2.1% of all infants born in the United States annually are conceived via some form of assisted reproductive technology (ART).

As new technology becomes available, fertility treatment is now accessible to more people, and success rates and safety are improving all the time. Financing fertility treatment can also be costly, but there are programs that can help with this.

How common is infertility?

Worldwide, 8–12% of couples experience fertility problems. At least 20% of infertility cases happen solely due to a problem with the male reproductive system. In addition, 19% of American females ages 15–49 years experience primary infertility after 1 year of trying. About 6% of married females ages 15–49 years experience secondary infertility. Black American and Latinx females are more likely to have infertility compared with American females who are white.

What are some complications of infertility?

If conception does not occur, it can lead to stress and possibly depression. Some physical effects may also result from treatment for infertility. For example, a female could get ovarian hyperstimulation syndrome (OHSS) from taking medications to stimulate the ovaries. Another complication can be an ectopic pregnancy.

Multiple pregnancies may also result from fertility treatment. If there are too many embryos, carrying all of them to term may cause health problems during the pregnancy.