Recently the Duchess of Cambridge gave birth to a healthy baby boy. The announcement from Buckingham Palace said "The Duchess of Cambridge has been delivered of a son."

This struck me as a very odd grammatical structure, that I don't quite understand. Of course I understand what is meant "She gave birth to a male child" and I presume it is put this way for the purposes of delicacy. But I was wondering if someone could explain how this grammatical structure works.

Recently the Duchess of Cambridge gave birth to a healthy baby boy. The announcement from Buckingham Palace said "The Duchess of Cambridge has been delivered of a son."

This struck me as a very odd grammatical structure that I don't quite understand. Of course I understand what is meant: "She gave birth to a male child" and I presume it is put this way for the purposes of delicacy. But I was wondering if someone could explain how this grammatical structure works.