Call The Midwife will take viewers through the cycle of life as the current series draws to a close.
The final episode will see the last-minute wedding of Nurse Barbara Gilbert, played by Charlotte Ritchie, and Reverend Tom Hereward, played by Jack Ashton, which has to be arranged in just three weeks so the bride's vicar father can conduct the ceremony before a missionary posting.
First-look pictures show Barbara dressed in a white fur-trimmed cloak over her wedding dress with a bouquet of red roses for her big day.
But before the wedding bells ring, the nuns open a new family planning clinic and Shelagh Turner, played by Laura Main, goes into labour.
Main has said that filming her character giving birth has made her want to have a baby of her own, despite having to watch "difficult" online videos of women in labour to prepare for the scene.
Main told the Radio Times that she "watched people giving birth on YouTube" to study for the big moment as well as speaking to the show's midwifery adviser, Terri Coates, about the different stages of labour.
Of the online videos, the actress said: "They haven't been edited too much and it's pretty difficult to watch! But the women have no inhibitions and they are very inspiring.
"Women who are giving birth go into a zone, don't they? You block it all out and just go for it."
She described filming the birth as "a very memorable day," saying: "After all, I started on the show as Sister Bernadette, a nun who thought she was infertile. And here I am as midwife Shelagh giving birth.
"It was just lovely. And nice for me as an actress to play another massive aspect of life.
"It makes me want to have a baby of my own."
The BBC One show has been a ratings success, with the sixth series building on previous outings to draw an average of 8.55 million overnight viewers and more than 9 million in consolidated ratings.
:: Call The Midwife airs on BBC One on Sunday March 12 at 8pm.