Interesting question! lol After DS was born, we were told to wait 4-6 weeks, preferably 6 but allowed at 4. She is going to be feeling really raw, bruised, and messed up in there, and she is bleeding a ton right now and for the next couple weeks. It really is like recovering from an injury - so think of it like that.
Not only do they make you do that because it could risk infection and she wont be healed up yet, but also for the first 4-6 weeks after giving birth, a woman is at her MOST FERTILE time EVER!!! So its really hard to prevent a pregnancy if you have sex during that time. You would be amazed at the number of women that go to their 6 week OB appointment just to find out they are pregnant!!! It happens allllll the time, its freaky.
So aside from all of that, when DH and I first had sex after DS was born (I don't remember if we waited the 4 or 6 weeks, but this is the general consensus among other women I have asked) it hurt pretty bad for me. And DH said that it was weird feeling for him too. Things just weren't back in place yet. He said a couple of months later, everything felt normal again. So just trust me, don't rush into it, it wont be fun for anybody lol. Wait it out, it will be so worth it, and there are other fun things you can do to feel good until then.