First Semen Release is Sperm Loaded, Most Potent for Assisted Pregnancy: Study

A new study that could change sperm collection in fertility clinics, claims that first fraction of ejaculate is more effective at conception.

"Ejaculate has always been considered as a whole. However, we believe that it is divided into two quite different phases due to its composition and physiological functions, aimed at achieving two equally important actions in terms of reproduction," said María Hebles, the study's lead author.

Led by Ginemed Assisted Human Reproduction Clinic, the study involved collection of ejaculate from 40 participants. The semen was collected in two separate containers, one for each phase. Study of sperm in the first fraction revealed it had enhanced population and less sperm DNA fragmentation compared to second phase.

"As we were expecting, the sperm from the first fraction of ejaculate were faster moving and the count was higher, and more importantly, they had higher DNA integrity than sperm from the second phase," Hebles added.

The study's hypothesis stems from semen's contrasting roles. While its first objective is to fertilize egg, its second objective is to prevent fertilization by sperm from other males. Researchers found that the first fraction of ejaculate accounts for up to 45 percent of the total semen ejaculated and is rich in sperm, acid phosphatase, citric acid, magnesium and zinc. The second fraction consists of secretions from the seminal vesicles which are detrimental to sperm, to meet sperm's second objective.

The study could change the current practice of sperm collection in assisted reproduction clinics which collect the entire ejaculate in one container.