Precum has a very slime chance of getting you pregnant, but it could.
"After ejaculation, whether by masturbation or sex with a partner, sperm may be left over in the urethra, the tube that semen travels through. Urinating between ejaculations flushes the urethra of these leftover sperm and clears the way for pre-cum. If sperm remain in the urethra from a previous ejaculation, they may be released with pre-cum. During unprotected vaginal sex, this could allow sperm to enter the vagina and possibly fertilize an egg, even if the man were to pull out before ejaculating."
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http://www.goaskalice.columbia.edu/0922.html