Fertility problems can be due to low or absent sperm numbers, or abnormal sperm movement or shape. A cause of abnormal sperm is not always found.
The testicles (testes) produce and store sperm. If they are damaged, it can affect the quality of the sperm. Damage to the testes can occur with:
- an infection of the testes
- testicular cancer
- surgery or injury to the testes
- undescended testes as a baby
- sterilisation/vasectomy – this can be reversed but it doesn't always work
- ejaculation problems during sex
- medications, eg, anabolic steroids or chemotherapy
- medical conditions – when you are unwell (eg, with flu or COVID) it can temporarily impair sperm quality
- illegal drugs, eg, marijuana and cocaine
- cigarette smoking as it reduces sperm quality.
- anatomical problems, eg, absence of vas (tube transporting sperm) or varicocele (enlarged veins in the scrotum).
Fertility problems can be caused by problems with ovulation (the monthly release of an egg from the ovaries) and by damage to the fallopian tubes. This includes the following:
- Pelvic infections, eg, chlamydia can damage the fallopian tubes.
- Polycystic ovarian disease or other ovulatory problems may stop you ovulating or mean that you ovulate less frequently.
- Endometriosis can damage the ovaries or fallopian tubes.
- Premature ovarian failure – this is when the ovaries stop working before the age of 40 years. However, fertility reduces in women after the age of 35.
- Fibroids (non-cancerous growths of the wall of the uterus) can sometimes contribute to infertility.
- Medications can impact on fertility. For example, some chemotherapy can damage the ovaries and antipsychotic medications can stop you ovulating.