Having a baby is generally a simple and natural experience. However, for some couples it can be difficult to conceive a child.

As a male, your fertility generally depends on the quantity and quality of your sperms. If the number of sperms you ejaculate is low, or if the sperms are of a poor quality, it will be difficult, and in some cases impossible, to get pregnant.

If you've been trying to get pregnant without success for a period of 12 months, and you've been having intercourse at least twice a week, it's worth visiting the doctor. If you're aware of factors that could have an impact on your chances of conceiving a baby, it's a good idea to seek help earlier on. Both you and partner should be tested for reproductive problems at the same time.

How common is infertility?

Infertility is a widespread issue. For about 20% of infertile couples, the problem is only in the male partner. For about 30% of couples the problem is in both partners. Therefore, the man contributes to infertility in around half of all cases.

About one in 20 men have low numbers of sperm, causing infertility. However, only about one in every 100 men has no sperm at all.

What are the symptoms of male infertility?

In most cases, there are no obvious signs of infertility. You'll usually have no difficulty with sexual activity, erections and ejaculation, and your semen will look normal to the naked eye. You'll need medical tests to help find out the cause of the infertility.

What causes male infertility?

Infertility can be caused by problems that affect sperm production or how the sperm travels. There are medical tests that can help work out the cause.

About two-thirds of infertile men have a problem where they make low number of sperms and/or sperms that don't work or function properly.

About one in five infertile men have other physical problems, including those who've had a vasectomy but now want to have children. Blockages (often called obstructions) in the tubes leading from the testicles to the penis can stop you from ejaculating sperm.

Other less common causes of infertility include:

Sexual problems that affect whether semen is able to enter the vagina (one in 100 infertile couples)

Low levels of hormones made in the pituitary gland (a hormone controller in the brain) that affect the testicles (one in 100 infertile men)

Sperm antibodies (proteins that fight against sperm, which are found in one in 16 infertile men). In most men, sperm antibodies will not affect the chance of a pregnancy, but in some cases it can reduce your fertility.

What are the genetic causes of male infertility?

Some changes to chromosomes or gene mutations can cause infertility because they harm sperm production or block the flow of sperm.

The most common genetic causes of infertility are chromosomal conditions that affect the way that sperm is produced. These include:

Klinefelter syndrome (a condition where you're born with an extra X chromosome)

Y chromosome deletions (a condition where you have genetic material missing from your Y chromosome that is important for sperm production)

Other genetic problems, such as Down syndrome.

Infertility can be due to mutations (DNA changes) in single genes, although it's far less common.

We think that other genetic conditions will be discovered in the future that will help explain other sperm production problems with no known cause.