In 1960 Prince Andrew was the first child to be born to a reigning British monarch since when?

Question

Which claimant to the Kingdoms of England and Ireland was de facto monarch of England after the death of Edward VI for just over a week in July 1553, and was executed in 1554?

Answer 1

1857
The last was Princess Beatrice, to Queen Victoria, born 14 April 1857. Successive monarchs had all their children before ascending to the throne (or had none).