Kylie Jenner announces birth of baby girl after months of keeping mum

US reality TV star Kylie Jenner announced on Sunday (Feb 4) the birth of her child with rapper Travis Scott, after months of rumours surrounding her pregnancy.

The 20-year-old said in a post on Instagram that her "beautiful, healthy baby girl" arrived on Feb 1 and apologised to fans for keeping her pregnancy a secret.

"I'm sorry for keeping you in the dark through all the assumptions," Jenner wrote.

"I understand you're used to me bringing you along on all my journeys. My pregnancy was one I chose not to do in front of the world."

[embed]https://www.instagram.com/p/BeycUmgFTWb/[/embed]

Jenner's half-sister Kim Kardashian, 37, and her rapper husband Kanye West announced the birth of their third child on Jan 16, a girl born to a surrogate.

Jenner's other half-sister Khloe Kardashian, 33, announced in December that she is six months pregnant with her basketball player boyfriend Tristan Thomas.

[embed]https://www.instagram.com/p/BeywIbWh_IW/[/embed]

Jenner, who has parlayed her family's reality TV show and a 101 million Instagram following into a lucrative cosmetics line, posted a teaser on Instagram to a YouTube video entitled To Our Daughter.

The arrival of her child quickly became the top trending topic on Twitter in the United States, surpassing #SuperBowlSunday just hours before the start of the big game.

[embed]https://www.youtube.com/watch?v=BhIEIO0vaBE[/embed]

She also released a video, To Our Daughter.

The Kardashian-Jenner family has become a pop culture powerhouse because of the access they allow the public. Members have documented some of the most intimate, and uncomfortable, moments of their lives for their reality TV show.

In September, tabloids wrote that the pregnancy for Jenner was a "happy" surprise.

[embed]https://instagram.com/p/BeycdselrTe/[/embed]

But neither she nor her family confirmed the news.

The birth of her daughter seems to have ended the push for total privacy.

Jenner's official YouTube page posted the 11-minute video that documented the entire pregnancy, including footage of her visiting the doctor with Scott, listening to the baby's heartbeat and even audio of the moment she gave birth.

Jenner had been conspicuously missing from the annual Kardashian-Jenner Christmas card. People poured over a recent Calvin Klein ad campaign and a magazine photo shoot looking for clues.

[embed]https://www.instagram.com/p/BeQKykugImS/[/embed]