It may be that one partner cannot contribute to conception, or that a woman is unable to carry a pregnancy to full term. It is often defined as not conceiving after 12 months of regular sexual intercourse without the use of birth control.
In the United States, around 10 percent of women aged 15 to 44 years are estimated to have difficulty conceiving or staying pregnant. Worldwide, 8 to 12 percent of couples experience fertility problems. Between 45 and 50 percent of cases are thought to stem from factors that affect the man.
Treatment is often available.
Causes in men
The following are common causes of infertility in men.
Semen and Sperm
Semen is the milky fluid that a man’s penis releases during orgasm. Semen 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 a man ejaculates and releases semen through the penis, the seminal fluid, or semen, helps transport the sperm toward the egg.
The following problems are possible:
- Low sperm count: The man ejaculates a low number of sperm. A sperm count of under 15 million is considered low. Around one third of couples have difficulty conceiving due to a low sperm count.
- Low sperm mobility (motility): The sperm cannot “swim” as well as they should to reach the egg.
- Abnormal sperm: The sperm may have an unusual shape, making it harder to move and fertilize an egg.
If the sperm do not have the right shape, or they cannot travel rapidly and accurately towards the egg, conception may be difficult. Up to 2 percent of men are thought to have suboptimal sperm.
Abnormal semen may not be able to carry the sperm effectively.
This can result from:
- A medical condition: This could be a testicular infection, cancer, or surgery.
- Overheated testicles: Causes include an undescended testicle, a varicocele, or 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 may include:
- Genetic factors: A man should have an X and Y chromosome. If he has two X chromosomes and one Y chromosome, as in Klinefelter’s 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: The urethral opening is under the penis, instead of its tip. This abnormality is usually surgically corrected in infancy. If the correction is not done, it may be harder for the sperm to get to the female’s cervix. Hypospadias affects about 1 in every 500 newborn boys.
- Cystic fibrosis: This is a chronic disease that results in the creation of a sticky mucus. This mucus mainly affects the lungs, but males may also have a missing or obstructed vas deferens. The vas deferens carries sperm from the epididymis to the ejaculatory duct and the urethra.
- Radiation therapy: This can impair sperm production. The severity usually depends on how near to the testicles the radiation was aimed.
- Some diseases: Conditions that are sometimes linked to lower fertility in males are anemia, Cushing’s syndrome, diabetes, and thyroid disease.