'Birgit [child of Steinar Torsson Fjågesund and Egeleiv Olavsdotter, born in Fjågesund] f. 1668 ...'
translation: Birgit [child of Steinar Torsson Fjågesund and Egeleiv Olavsdotter, born in Fjågesund] b. 1668
The year 1668 undoubtedly came from the listing of the birth in the family sermon-book, which apparently followed the Julian calendar (based on her brother Olav's birth information). It is assumed that Bergit was born about Feb or Mar 1669 according to the Gregorian calendar (which was not officially adopted in Norway until 1700), as anything much earlier than that was too soon after the birth of Olav.