Sue and Noel Radford, the parents of Britain's biggest family, are expecting their 18 baby.
The 'thrilled' couple made the announcement via an interview with The Sun newspaper which they then shared with their Facebook followers along with the message: "We are feeing incredibly lucky and blessed."
And in a poignant reference to the baby she lost earlier this year, Sue added: "We truly believe this baby is a gift from Alfie."
Baby Alfie Thomas – the couple's 18 child - was stillborn in July.
Sue broke the sad news on Facebook, saying: "Our beautiful baby boy Alfie Thomas was born sleeping at 7.53am...he was so perfect in every way our hearts are breaking you will always be a huge part of our lives Alfie know that we loved your very much Xx."
Speaking to The Sun, Sue and Noel said their new baby was 'the perfect Christmas gift' after the loss of Alfie.
They don't yet know if it's a boy or a girl, but have just had the first scan which confirmed all was going well at 14 weeks.
The latest arrival will join Chris, 25, Sophie, 21, Chloe, 19, Jack, 17, Daniel, 15, Luke, 14, Millie, 13, Katie, 12, James, 11, Ellie, nine, Aimee, eight, Josh, seven, Max, six, Tillie, four, Oscar, three and Casper, two.
But the couple said of the new baby: "This will be the last."
Sue, 39, told The Sun: "We are really, really excited. It is the best news I could hope for after a difficult year. It feels like a blessing.
"We weren't planning on getting pregnant so quickly. I wasn't sure it would happen, to be honest.
"But we are so glad it has and the children are all really happy.
"This will be the last, 18 is enough. I've had bad morning sickness but it has stopped now so I am just waiting for the cravings.
"I am sick whenever I smell Noel's aftershave so I have banned him from wearing it.
"I'm used to the pregnancy stuff now. I know I will be stuffing my face with cream cakes within a few weeks."
Sue and Noel – who own and run a family bakery - live in a former care home with 10 bedrooms in Morecambe, Lancashire.
All the kids still live at home apart from their daughter Sophie. They are also enjoying being grandparents - Sophie gave birth to their second granddaughter, April, this year.
Sue was pregnant with Alfie at the same time as Sophie and their due dates were five weeks apart.
Sue said: "It was really hard because I was so far along. Now I have been told to rest as much as possible but everything is fine.
"The baby is really active. I think it's a girl because the girls have always been hyper when I was pregnant with them.
"I feel like it has come just at the right time. It is the perfect Christmas gift."