For the House of Windsor at least, the royal couple remained the gift that keeps on giving, and just in time for the holidays. Their wedding, watched by 2 billion people on six continents, helped usher in a renaissance of a family once stained by constant scandal. Polls show that support for the monarchy has never been higher in the modern era. After recent doses of racy press — including a topless photo of the duchess and photos of Prince Harry playing naked pool — the pregnancy offers the family a more traditional talking point.

Royal-watchers say the birth could mark the evolution of the duke and duchess’s roles in the public eye, with Prince William in particular expected to take on an ever-expanding list of official duties next year.

“This is the Christmas present people have been hoping for, and what a royal family is all about — renewal,” said Robert Lacey, royal biographer and author of “The Queen: A Life in Brief.” “There is nothing like youth to revive monarchy. This announcement is about the next stage to come, with the young couple more and more in the public eye as the next generation of royal family.”

Eliza Mackintosh contributed to this report.