Call the Midwife creator Heidi Thomas has revealed that season 12 will revisit a storyline concerning the thalidomide tragedy, which was first introduced in a previous series.
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Back in season four, pregnant patient Rhoda Mullucks (Liz White) came to Nonnatus House seeking help for her morning sickness symptoms.
WATCH: Are you looking forward to season 12?
After being prescribed thalidomide by Dr Turner (Stephen McGann), Rhonda's daughter, Susan, was born with birth defects in season six as a result.
In an interview with RadioTimes.com, Heidi said that the Mullucks family will return to screens in season 12, with Rhonda set to have another baby. The 59-year-old creator explained that the new pregnancy "puts them under a certain amount of pressure and gives them a lot to worry about".
She added: "We haven't actually been with that family for five years, so we're picking up the pieces for them and it makes for a very special Christmas special."
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Heidi also confirmed that the new series will welcome some fresh faces, as well as returning favourites. She teased: "Something rather wonderful happens to Trixie, Lucile has to contend with a reasonable amount of sadness, and what else can I say? We have a new nun coming to join the line-up, Sister Veronica."
The new series will revisit a previous storyline
The update on season 12 comes just days after the show announced a short break in filming for the summer.
The series shared a behind-the-scenes snap showing actors April Rae Hoang, Alice Brown and Ned Shaw, who play Turner children May, Angela and Teddy respectively, dressed in costume.
The caption read: "Filming days can be very long, and the hours very inhospitable - and so our production likes to reward our team with a decent break midway through so that they can return refreshed to complete the series.
Fan favourite Trixie will be back for the Christmas special
"So how are we doing? Really, really well! We have already completed Christmas filming, and are well into Series 12! When we return from our summer break, we have the last half of our stories to film, and won't complete that till the early winter. Call the Midwife is truly a four-seasons job!"
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