Britney Spears had an abortion after getting pregnant with Justin Timberlake, according to excerpts from her upcoming memoir.
The pop star's new book, The Woman in Me, focuses in part on her 13-year conservatorship under her father James Spears.
Justin was "not happy" about Britney being pregnant, according to parts of the book published in People magazine.
"He said we weren't ready to have a baby in our lives," she says.
The pop star duo dated in their late teens between 1999 and 2002.
Justin was "so sure that he didn't want to be a father", Britney writes.
She says she did not know if having the procedure was the right decision, and that she would not have had an abortion if the choice was "left up to me alone".
"For me, it wasn't a tragedy. I loved Justin so much. I always expected us to have a family together one day. This would just be much earlier than I'd anticipated."
The BBC has reached out to Justin Timberlake for comment.
Britney has since gone on to have two children - Sean Preston, 18, and Jayden James, 17 - with her second husband, Kevin Federline. Justin is married to actress Jessica Biel and they have two sons.
The 41-year-old's book is set to be published on 24 October - two years after the end of her conservatorship which she says "stripped her of her womanhood".
The singer has previously called the arrangement abusive. It was set up by her father in 2008 after she experienced a public breakdown, during which she shaved her head.
She testified in court in 2021 that she had been drugged, forced to perform against her will and prevented from having more children.
Her father had power over her finances and career decisions as well as major personal matters, such as her visits to her teenage sons and whether she could get remarried.
In her book, she offers more insights into the "soul-crushing" arrangement.
"The woman in me was pushed down for a long time," Britney writes. "They wanted me to be wild onstage, the way they told me to be, and to be a robot the rest of the time."
Shaving her head and "acting out" were her ways of pushing back. "But under the conservatorship I was made to understand that those days were now over," she says.
Among several allegations, she says her father repeatedly told her she looked fat and infantilised her. She claims the conservatorship eventually stripped her of her passion for performing.
The book also features more joyous moments from her childhood, including when she went back to high school in Kentwood, Louisiana, in search of normalcy.
"There was something so beautifully normal about that period of my life: going to homecoming and prom, driving around our little town, going to the movies," she writes.
The normalcy would be short lived. Britney says she was quickly called back to performing, signing a deal with Jive Records at age 15, later going on to release hits Baby One More Time and Oops!... I Did It Again.
Since the end of her conservatorship, Britney has recorded several more hits. She also married her boyfriend Sam Asghari, though the couple divorced after a year.
She says the years after her conservatorship have allowed her to construct a new identity.
"I've had to say, Wait a second, this is who I was - someone passive and pleasing. A girl. And this is who I am now - someone strong and confident. A woman," she writes.