The BBC confirmed today that the '50s drama, which focuses on nursing nuns in the East End of London, will return to screens earlier than expected.
Midwife, starring Miranda Hart, Jenny Agutter and Pam Ferris, was recommissioned after only two episodes following its huge viewing figures.
BBC's drama controller Ben Stephenson said: "Following its huge success, we simply couldn't resist treating audiences to a Call the Midwife special this year - our Christmas present for all BBC One viewers."
Executive producer Pippa Harris teased: "As the nights draw in and Christmas approaches, the residents of Nonnatus House pull together to celebrate the season in their own very special way.
"Christmas celebrates one particular birth, and so it's especially fitting for BBC One to pay a visit to these much-loved characters, whose daily lives revolve around the joys and tribulations of childbirth."
Created by Heidi Thomas, the period medical series broadcast its first run of six episodes from January on Sunday nights.
> Call the Midwife named BBC One's most successful new drama series
Watch a clip from BBC One's first series of Call the Midwife below: