Australian-born Crown Princess Mary, who is expecting twins, was Saturday admitted to Copenhagen University Hospital, the Danish royal palace said.
The palace confirmed in August that the 38-year-old wife of Crown Prince Frederik was expecting twins and that the birth was due sometime in January, DPA reported.
Earlier this week, the palace refuted reports that the princess had already been admitted to a maternity ward at Copenhagen University Hospital where the couple's two previous children were born.
Their five-year-old son Christian - second in line to the throne after his father - was born in October 2005, and daughter Isabella, 3, in April 2007.
Mary met Frederik, 42, in a Sydney pub during the 2000 Olympics. They were married in 2004.