Girlfriends

What a blessing it is to have girlfriends!  Of recent years, I have been intrigued by Luke 1:56.  This verse comes after the annunciation to Zechariah and Elizabeth, after the Annunciation to Mary, just after the Magnificat.  Mary has gone to visit Elizabeth, where we learn the power of the presence of Christ.  Even as pregnant-with-Jesus Mary enters the room, unborn-John-the-Baptist senses the presence of his Lord and "leaps with joy" in Elizabeth's womb.  And then, in verse 56, "Mary stayed with Elizabeth for about three months and then returned home." (NIV) 

I start wondering...what was Mary doing there?  Why did she go to visit Elizabeth in the first place?  Why travel from Nazareth to Galilee - who needs to be taking a journey like that in the midst of so much stress?  And why stay three months?