Jaylene,
apparently you naturally pee and sweat like crazy for several weeks after giving birth. That's your body getting rid of that extra 25% blood volume you've been hauling around!
Thee are lots of foods that are full of good nutrients and are also natural diuretics (watermelon is a good one).
Not to freak anyone out, as I don't know if the study has been independently reproduced with the same results, but I read a new study in my first tri in which researchers found that green tea significantly reduces your body's ability to absorb folic acid. I decided to avoid green tea for my pregnancy, just in case. It's hard, though, because green tea has so many other huge health benefits. I plan to keep drinking it after birth.