First aid rules in pretty much every game ever made. The times are either way off or the effects are way too good. Sometimes, they're both. ("I roll a 15 on my healing check, the character can spend a second wind and is now fully conscious! And it only took six seconds!")
Speaking of which, any game which had more than one (or, at most, two) medical skills would probably be crazy - while in reality there is a lot to differentiate a paramedic from a nurse from a doctor, in a game, we don't need that level of granularity (although I know more than a few paramedics who would be miffed to be considered "less skilled at first aid" than, say, a doctor... as paramedics are better first responders than most doctors).
I have to agree with the pregnancy thing, too, mentioned above. Although, to be fair, in a post-apoc game we actually had a rules system set up that covered things like infections, radiation illness, stds, pregnancy, drug overdoes, and the like. And it all followed one very easy mechanic. But we were trying to cover a different sort of game than your usual D&D-type fantastic adventure.