This intercourse advantage is even greater for men with oligospermia.

It found no significant relation between oligospermia and being underweight.

Many conditions listed may also cause various degrees of oligospermia rather than azoospermia.

The diagnosis of oligospermia requires a work-up (listed in Male infertility).

In most cases of oligospermia including its idiopathic form there is no direct medical or surgical intervention agreed to be effective.

There are many causes for oligospermia including:

There currently are no effective medications to treat oligospermia, so other assisted reproductive technologies are used.

A review in 2013 came to the result that being overweight significantly increases the risk of oligospermia and azoospermia in men.

Defects in this area can lead to oligospermia or azoospermia, however, a tight genotype-phenotype correlation has not been achieved.

Workers exposed to high levels are at risk for granulocytopenia, macrocytic anemia, oligospermia, and azoospermia.

Idiopathic oligospermia (oligoasthenoteratozoospermia)

Hypospermia would only usually be a factor in infertility if the two conditions (hypospermia and oligospermia) are combined.

In case of proven fertility but unresolved pelvic pain, even one or both partially obstructed ejaculatory ducts may be the origin of pelvic pain and oligospermia.