The youngest child of former Bulgarian king and prime minister Simeon Saxe-Coburg, Kalina is pregnant, Trud daily reported.
Kalina's baby will be Simeon's 11th grandchild.
The happy news was announced during the opening mass of the newly built church named after the Orthodox Christian Saint Ivan Rilski (the Miracle Worker).
The church is special for Kalina because it was built on the soil where she consented to marry famous explorer Kitin Munoz.
The church is erected in Tsarska Bistritza, which is 75 km to the south of Sofia.
Archbishop Giuseppe Leanza, the Apostolic Nuncio to Bulgaria attended the mass of the church.
Princess Kalina and Kitin wed four years ago in a simple yet traditional ceremony in a mountain resort in southwest Bulgaria.