A sperm’s quest to fertilize an egg is not easy. Of the roughly 250 million sperm ejaculated into the human vagina during intercourse, fewer than one in a hundred will survive the perilous trek up the hostile, acidic chamber to the cervix. If the female is set to ovulate soon, the cervix will allow the frisky, foreign interlopers inside. If not, they’ll “drown” in a thick flow of cervical mucus. Sperm that enter into the cervix must next decide to go left or right – for a human female has two fallopian tubes with an ovary at each end, and usually just one releases an egg. Perhaps a hundred sperm will enter a fallopian tube, and maybe one or two will actually reach the egg for a chance at fertilization.
https://www.realclearscience.com/blog/2018/05/03/do_sperm_battle_other_sperm.html
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