Watch: Stacey Solomon is pregnant!
Posting a picture of her and Swash and their children, Solomon said: “We are growing another pickle.
“We’ve never felt so grateful… I have no words. We didn’t think we would get the chance.
“We love you all to the moon and back.”
The TV star, 31, is already mum to sons Zachary, 13, and Leighton, nine, from previous relationships.
Swash has a 13-year-old son, Harry, from a previous relationship, and the couple share two-year-old son Rex.
Sharing a picture of a negative pregnancy test on Instagram, Solomon said they had been hoping for "another pickle" for a while.
“For a really long time we've been trying for another pickle. It didn't work out and this was our news quite a few times,” she said.
“We decided we were so lucky already to have our boys.
“It is our biggest privilege in life and we are so grateful to be parents so we stopped trying and counted ourselves so, so, so blessed already.”
She also shared a letter revealing that she had suffered a miscarriage.
Solomon said she had been feeling “yuck” lately but hadn't wanted to check.
“But yesterday we went to check what was going on… and we were so grateful to hear an extra heartbeat," she said.
The couple have now told their other sons that they are expecting.
“Boys we are so so so excited for you all,” Solomon wrote.
“You’re already the most incredible brothers we could have ever imagined raising.”
The star was inundated with messages from fans and friends after sharing her lovely news.
Saturdays singer Mollie King sent "huge congratulations" while Love Island host Laura Whitmore said she was "so happy" for Solomon and her family.
Solomon's fellow Loose Women panellist Nadia Sawalha wrote on Instagram: "Phew! Have been praying it would stay a secret for as long as you wanted !!!! Love you all."
Watch: Joe Swash lets slip his wedding date on Loose Women