Why "It is a cradle" not accepted? Isn´t a crib and a cradle the same thing?
I would also say it's correct; the movie The Hand That Rocks the Cradle was translated as *A Mão que Balança o Berço" in Brazil.
I would just add that there's a slight difference between cradle and crib, cradle basically being able to rock sideways, while crib is stationary. In Brazil, cradles are not so common, I would think, so if you wanna be very specific, you can say berço (de) balanço, as in "rocking cradle".
A crib is a bed with open walls around it. In the US, its size is exactly regulated. A cradle is much smaller, in addition to being able to rock. Google translates cradle as cunabula.