Is precum real? Who has conceived by pre ejaculation?

  I an Mom of two beautiful babies, 5 year old boy and little princess soon to be two and a lovely husband.  It seems I can't shake theses new baby blues though.  We've had the talk about trying for a third both agreeing we would love another but not sure it when.  Although we aren't actively trying,  I've finally removed my iud had for almost two years and now we aren't using any birth control. ( ps I'll never use birth control again.. another  story).  But of course he isn't quite there yet to actively try and ejaculate lol he's a nervous reck as always but isn't fighting the idea of me becoming pregnant.  I've been tracking my ovulation and want to know if there is a chance of woman conceiving through pre ejaculation?  Has this ever happened to anyone here? Thanks