The announcement means he will become the first British prime minister to marry in office for 250 years
British Prime Minister Boris Johnson and his girlfriend Carrie Symonds announced on Saturday they are expecting their first child together and are engaged to be married.
The couple have been living together in Downing Street since Johnson became prime minister in July, with Symonds the first unmarried partner to live openly with a British leader in recent history.
"The prime minister and Miss Symonds are very pleased to announce their engagement and that they are expecting a baby in the early summer," the couple said in a statement.
The 55-year-old Johnson took office in July and led his Conservative Party to a decisive election victory in December.
The announcement means he will become the first British prime minister to marry in office for 250 years.
The couple’s relationship was the subject of scrutiny during his bid to take over from Theresa May as prime minister last summer after police were called to Symonds’ home by a neighbour who heard an apparent row between them.
Symonds, 31, said in a message posted on Instagram that she had kept news of her engagement secret until now.
"I wouldn't normally post this kind of thing on here but I wanted my friends to find out from me," she said.
"Many of you already know but for my friends that still don't, we got engaged at the end of last year and we've got a baby hatching early summer," Symonds said, adding: "Feel incredibly blessed".
Johnson was congratulated by members of parliament, including his former finance minister, Sajid Javid, who resigned after losing a power struggle over who should control Britain's economy.