Among the births and happy family life it seems Trixie Franklin (played by Helen George) will suffer yet another blow.

The preview shows the midwife sobbing as she talks with her dentist boyfriend Christopher Dockerill (Jack Hawkins).

“I’m not asking for help,” the nurse asserts, as her beau replies: “You need it."

The reason for Trixie’s distress is not revealed, but it could be a re-emergence of old problems.

Trixie was previously involved in a gripping storyline as the fun-loving party girl grappled with her problems with alcohol.

She has since sought help for her issues, remaining teetotal and attending Alcoholics Anonymous, but could viewers be about to see her struggle again?

The trailer also hints at other exciting happenings for Nonnatus House and its occupants.

A glimpse at new midwife, Lucille Anderson (Leonie Elliott), can be seen as she acclimatises to life in Poplar after moving over from the West Indies. 

The addition of the character will reflect the experiences of the Caribbean nurses who came to England in the 1960s to work for the expanding NHS.

Meanwhile, Nurse Crane (Linda Bassett) is shown with the policeman she butted heads with in the Christmas special. 

Will they remain at loggerheads, or is the spinster set for an unlikely new romance?

Call the Midwife will return to BBC One soon.