Why did Elizabeth keep herself hidden while pregnant?

In Luke 1:24-25 we read: > 24 After these days his wife Elizabeth conceived, and for five months she kept herself hidden, saying, 25 “Thus the Lord has done for me in the days when he looked on me, to take away my reproach among people.” Why did she keep herself hidden? Certainly something to do with the fact that she was barren and isn't any more... But why would that cause her to hide this fact?