She decided to 'put/give the baby up for adoption'. [=to make it possible for other people to adopt the baby]
They chose 'adoption' because they couldn't have children of their own.
the unanimous 'adoption' of the resolution by the Senate
(..) Had fallen in love when he was very young With a beautiful girl named Susan wells, And how buddy was born And put up for adoption by his mother, And how she had later passed away. I... I told him his father Had never even known that Buddy was born, (..)2003 Elf