Prime Minister Boris Johnson's partner, Carrie Symonds, gave birth to a "healthy boy" in a London hospital on Wednesday, a spokesman for the couple said.
The news came as a surprise since Symonds, 32, was not expected for several weeks, but was told "very well".
The birth comes just days after the 55-year-old Johnson returns to work after being hospitalized with coronavirus, including three nights in the intensive care unit.
"The Prime Minister and Ms. Symonds are pleased to announce the birth of a healthy boy in a London hospital this morning," the spokesman said.
"Both mother and baby are doing very well."
"The Prime Minister and Ms. Symonds would like to thank the fantastic maternity team of the NHS (State National Health Service)."
The announcement explains why Downing Street officials are reluctant to confirm that Johnson will appear at his weekly Q&A session with MPs.
Foreign Minister Dominic Raab, who represented him during his illness, is expected to take his place later on Wednesday.
Johnson is said to have at least five children, including four with his second wife Marina Wheeler, whom he separated in 2018.
Since the beginning of 2019, he has been in public with Symonds, a former communications leader of the Conservative Party.
They announced in February that they were getting married and were expecting a baby "in early summer".
On their Instagram page, which is private but whose details have been reported in the media, Symonds announced that they got engaged at the end of last year.
Johnson did not return to work until Monday, two weeks after he was discharged from the hospital because of an illness that he said "could have gone either way."
Symonds had moved out of his Downing Street apartment before he fell ill, but later reported that she herself had symptoms of a coronavirus. She was recovering at home.
She has held back as "first friend" and largely stayed out of the election campaign last December in which Johnson achieved the best result for the conservatives since the 1980s.
After leaving the Conservative Party, she was an enthusiastic environmental activist and worked for a charity to protect the oceans.
(Except for the headline, this story was not edited by NDTV staff and published from a syndicated feed.)