Helen George says 'Call the Midwife' will come to an end to match the accounts of the time period.
The 35-year-old actress - who plays Trixie Franklin on the BBC period drama - has said the series will eventually end, as the characters are based on the memoirs of the late midwife and writer Jennifer Worth, so cannot go on forever.
Talking to Phillip Schofield and Holly Willoughby on Wednesday's (06.11.19) episode of 'This Morning', Helen said: "The nuns faded out in the community so there is a ceiling point to it, but you never know, there might be a spin-off."
She quickly quipped: "I'm joking, I don't know that. Imagine the nun's going into the 80s."
Helen also revealed details on the highly anticipated Christmas special, which sees the lovable community of nuns head to the Outer Hebrides.
The former 'Strictly Come Dancing' participant added: "It was beautiful because we got to film in the Outer Hebrides for four weeks and it's the most stunning place, so it becomes a character in the show, it's so cinematic. We were shooting outside a lot - it was really cold - because the surrounds are just so beautiful we didn't want to ignore it.
"But we go up to the Outer Hebrides because there's a small community without any medical help advisers, nurses or doctors. There's a community in need, so we go up and help in our own way."
Whilst filming in the Isles, Helen was reunited with co-star Miriam Margolyes after her debut during last year's holiday special.
However, the 'Nativity Rocks!' star admitted she didn't miss Miriam's foul breakfast habit.
Helen admitted: "She's really fun, she's really naughty and she eats a raw onion every day for breakfast."
A horrified Holly questioned why, to which Helen replied: "Because she said it's good for her heart and for her health.
"I don't go that close to her after breakfast, I stay my distance."