These three terms refer to different seminal alterations. First, hypospermia is characterized by a low semen volume in the male, specifically, less than 1.5 mL. However, it is possible that the rest of the semen parameters are within the normal range.
Secondly, aspermia is the total absence of ejaculation in the male. Therefore, it is also known as anejaculation.
Finally, azoospermia refers to the absence of sperm in the ejaculate. The male is able to ejaculate a normal volume of semen, but it is not possible to find any sperm. Therefore, pregnancy would not be possible in a natural way.