This isn't when you install the AC one day too late or keep the flannel sheets on one night too long. Dr. Oz explains why we sweat and how much is normal -- and when it's an indication that something is seriously wrong. 

Animation produced by Visible Productions Inc.

After years of trying to get pregnant, doctors told Kelsi Pierce it would be near impossible for her to conceive a child. However, Kelsi got the surprise of her life when her mom volunteered to be her surrogate — and she found out she, too, was pregnant!