Asthenozoospermia is a decrease in the percentage of motile sperm in a sperm sample and it is identified by means of a seminogram or semen analysis.
Nowadays, seminograms are a basic tool which provide us with information in order to evaluate a man’s fertility and they are very useful when determining personalised treatment for the couple concerned. The analysis can be used to evaluate numerous factors such as the concentration, motility and morphology of sperm present in the ejaculate, amongst others.
According to the criteria included in the 5th edition of the World Health Organisation (WHO) (2010) manual, a man has asthenozoospermia when less than 32% of sperm in the ejaculate have progressive motility (sperm which move around) or when there it less than 40% total motile sperm (motile sperm which do and do not move around).
Asthenozoospermia causes infertility because when sperm do not have progressive motility, they are unable to reach the egg and fertilise it and, consequently, pregnancy does not arise.
The reasons are not very well understood, but it is known that sperm motility can be affected by factors such as:
- Presence of antisperm antibodies
- Excessive consumption of alcohol or other drugs (tobacco, marijuana, etc.)
- Age: motility decreases from 45 years of age
- Exposure to toxic products (fertilizers, chemical solvents)
- Infections in semen
- Problems in testicles
- Teratozoospermia: abnormal sperm morphology, particularly in the tail and middle section
- Poor diet
- Chemotherapy and radiotherapy
- Inappropriate habits which increase the temperature in testicles (saunas, tight clothing…)
Depending on how advanced asthenozoospermia is, different types of treatment can be contemplated in order to achieve pregnancy. The most successful of these is ICSI (intracytoplasmic sperm injection) because it ensures that the sperm gets into the egg. This reduces the risk of a fertilisation failure to an absolute minimum, as can happen in classic in vitro fertilisation (IVF) or in artificial insemination.
There are some methods which can be used in order to improve sperm motility. Amongst the most significant are eating habits. Certain products which are rich in essential amino acids such as L-carnitine and antioxidants, when combined with a healthy lifestyle, help to improve sperm quality.