The first fraction of ejaculate is the most effective for conception

Sperm in the first fraction of ejaculate are more numerous, move more and present better quality DNA than those lagging behind. This is the conclusion of a study led by the Ginemed fertility clinic, which confirms that while the objective of the first fraction is to fertilise the egg, the second phase is so that no sperm from any other male has a chance to fertilise it.

A study led by the Ginemed Assisted Human Reproduction Clinic analyses the advantages of using fractions of ejaculate separately in in-vitro fertilisation as a way to improve the sample of the semen.

The researchers' hypothesis was that, comparing the different fractions of semen in an ejaculation, the first would contain sperm with better seminal parameters and could be used as an effective method for selecting sperm prior to fertilisation.

"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," María Hebles, co-director of the reproduction laboratory at the Ginemed Clinic in Seville and lead author of the study, explains to SINC.

The first objective of ejaculate would be to fertilise the egg and the second so that no other male has the opportunity to fertilise it. Therefore, the first fraction is characterised as having protective components such as zinc, whereas the second contains elements that can cause damage to sperm.

However, for their use in assisted reproduction techniques, the liquid is normally collected in a single container, and therefore both phases are mixed together. This could have a detrimental effect on the sperm population," adds Hebles.

The Two Phases of Ejaculation

Emission is when the sperm is prepared for release from the body, just before expulsion. It is mixed with several substances including fluids from the seminal vesicles and prostate, to form semen, ready for use.

Ejaculation Proper is when the semen is released from the penis in spurts, occurring once enough semen is produced to be ejaculated through the urethra. Once this process has started, it is impossible to stop

Based on this, the specialists asked 40 participants to collect the ejaculate separately into two containers, one for each phase. They then separated the first and the second phase and studied the characteristics of the sperm in each of them.

Data suggests that the first phase contains an enhanced subpopulation of sperm, with less sperm DNA fragmentation. Therefore, the use of sperm from this fraction can have a positive effect on fertilisation and embryonic development.

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