Pregnancy

I'm always learning something new about the Chinese culture.  Today in Chinese class we discussed pregnancy.

Babies are born in the hospital just like in the states.  After the hospital the mother must stay at home for one month.  Sounds nice.  Nothing wrong with staying inside for a month when you have a new baby at home.  Here's the part that's hard to understand.  The mother cannot bathe, shower, or wash her hair for ONE MONTH.    It has something to do with pain but I'm still trying to understand the reasons for this strange tradition.