The causes of male infertility are multiple. The primary cause is deterioration in sperm quality. Unlike female infertility, male factor infertility decreases with age just slightly. Deterioration of sperm quality is usually caused by the diseases listed below. Male factor infertility can be of congenital origin.
There are several types of decrease in sperm quality: oligospermia, asthenospermia, teratospermia, aspermia.
Oligozoospermia is a condition of decrease in number of sperm in the ejaculate. The normal range of the sperm count is above 20 million/ml.
Astenozoospermia is a reduction of sperm motility. Only progressive motile spermatozoa can fertilize the oocyte. If their count is reduced then the conception rate also decreases.
Teratozoospermia is an increase in perecantage of spermatozoa of abnormal form (morphology).
Azoospermia is a condition characterized by the total absence of sperm cells in the sperm. Azoospermia can be caused by obstruction or underdevelopment of ductus deferens or by abnormalities in production of sperm cells. Both conditions may be geneticly conditioned.
If oligospermia is caused by the problems in sperm transport (obstruction) it is called obstructive oligospermia. If oligospermia is caused by a problem in sperm production, it is called non-obstructive oligospermia (as there is no obstruction in this case).
It can often occur that, several conditions are combined e.g. oligoastenospermia (both total sperm count and progressive motile sperm percentage are reduced), oligo-asteno-teratospermia (total sperm count, percentage of progressive motile sperm and normal morphology forms are reduced).
More details on the impact of sperm count, motility and morphology can be found in the information on the conception rates.
Reduction in sperm quality can be caused by problems in sperm cells production or transport.
Problems in soperm production may be caused by:
- Epidemic parotiditis (mumps) in childhood
- Hormonal disorders
- Operated tumors
- Genetic causes
- Environmental factors
- Drug and nicotine abuse
Sperm transport disorders can be caused by inflammation, varicocele, and congenital disorders (refer to genetic causes listed in this section). In this case even if the sperm quantity is sufficient, the spermatozoa still can’t move to the female reproductive tract since the ducts are obstructed. Sperm transport disorders can be also caused by sterilization in the past.
Sometimes the cause of infertility can’t be defined exactly.