Phimosis is where a man's foreskin doesn't retract at all... ever. My DH has this, and he thinks nothing of it because it doesn't cause him any bother. From a TTC point of view though, I'm worried.
Allow me to be graphic! If you are of a sensitive disposition please look away now
The foreskin seems to get in the way when it comes to ejaculation. It kind of um, oozes out and doesn't travel far. It seems logical to me that this might cause problems with TTC because semen would be deposited so low in the vagina (compared with men who can ejaculate "normally") the sperm just won't be able to swim all that way
Is it worth suggesting he visit the GP? Naturally, the idea of having to get his bits out for a doctor is absolutely horrific for him, plus the added fear that they might recommend circumcision. I'm not sure I'll be able to convince him to go, even though I've heard there are less drastic treatments out there...