The pop star and former X Factor judge Cheryl has given birth to a baby boy.
The 33-year-old singer said on her Instagram page that she and One Direction's Liam Payne had welcomed the new arrival on Wednesday.
A photo showed Liam cradling an infant with dark hair.
The caption below the picture read: "On Wednesday 22nd March Liam and I became parents to an incredibly beautiful, healthy baby boy, weighing 7lb 9 and looking like a dream.
"Although he still doesn't have a name he is already stealing hearts."
She added: "We are all madly in love and overwhelmingly happy with our little arrival.
"Happy Mother's Day to all the mothers around the world.
"A day that now has a different meaning to me forever."
Liam, 23, posted the same photo on his Instagram account, writing: "My close friends and family know there are very few times when I'm left speechless...wow!
"I'm incredibly happy to welcome our new baby boy into the world, it's a moment that I will never forget for the rest of my life and my favourite memory I have so far."
He added: "I'm completely in awe of his incredible mother and how she has been the whole way through this, she's really made my dreams come true.
"We haven't named him yet but he's already capturing hearts including mine.
"I feel very blessed.
"Happy Mother's Day everyone!"
Cheryl's former Girls Aloud bandmate Nadine Coyle was among those offering congratulations.
She tweeted: "Congratulations @cherylofficial I am so so happy for you & your precious little boy & family! Sending you loads of love!"
Reality TV star Khloe Kardashian also tweeted: "Congratulations doll!!!!! God bless your family!!!!! I couldn't be happier for you love!"