Fellowship in Sexology and Psychosexual Counseling. For More Info WhatsApp- 9604715783. The clotting enzyme from the prostatic fluid and fibrinogen from seminal vesicles form a coagulum which is dissolved in next 20 minutes by fibrinolysis from prostatic fluid. Sperms remain immobile for some minutes after ejaculation; however, fertility should remain supine on the bed for about 30 minutes after the coitus, especially during the fertile period.