Spears expressed her desire to have more children last year, telling a judge she wasn't able to make her own birth control decisions under Conservatives.
Britney Spears said she is "having a baby" with her fiancé Sam Asghari in an Instagram post on Monday.
Spears, 40, revealed her desire for more children less than a year ago, when she said she was unable to make her own birth control decisions while she was under a guardianship, which expired in November. .
Spears said she took a pregnancy test when she noticed that her belly was "growing," despite her recent weight loss after air travel. At first, Asgari joked that she was "food pregnant," but Spears decided to take a test anyway.
"So I took a pregnancy test... and uhhhh ok... I'm having a baby," she wrote.
A spokesperson for Spears did not immediately respond to a request for comment. Asgari declined to comment.
Asgari later posted on his Instagram account, noting that marriage and children are part of a "strong relationship" filled with love and respect.
"Fatherhood is something I've always looked forward to and I don't take it lightly," he wrote. "It's the most important thing ever."
Spears has two teenage sons, Sean and Jaden, with ex-husband Kevin Federline.
His lawyer, Mark Vincent Kaplan, said Federline was aware of Spears' position.
Kaplan said, "He wishes her a happy, healthy pregnancy and congratulates her and Sam Asghari as they plan the excitement of parenthood together.
Spears said she plans to avoid going out because of the paparazzi, who harassed her during her two previous pregnancies, noting her experiences with perinatal depression and how much she publicly discussed the experience at the time. There was little discussion.
"But now women talk about it everyday," Spears wrote. "Thank you Jesus, we don't have to keep that pain a secret."
In public testimony last year, Spears expressed her desire to have more children.
Spears told Los Angeles County Superior Court Judge Brenda Penney that she wanted to remove her intrauterine device but her patrons would not allow it.
"I wanted to take the IUD out so I could start trying to have another baby," she said in June. "But this so-called team won't let me go to the doctor to get it out because they don't want me to have any more kids."
Asgari proposed to Spears after her father petitioned for an end to the conservatism, which officially ended at the end of last year. The couple started dating in 2016 and got engaged in September.