Does masturbation affect a man's fertility and ejaculation volume? Has volume got anything to do with fertility in the first place, and if so, should I stop masturbating?
Apart from reducing the volume of the next ejaculation slightly (and very temporarily), no, it doesn't affect your fertility. There are many, many millions of sperm cells in a regular-size ejaculation, and all it takes is one to get a woman pregnant – so I doubt abstaining from masturbating would have much effect.