Kylie Jenner, with rapper boyfriend Travis Scott performs. Jenner announced the birth of her baby girl born Thursday. It’s the first child for the 20-year-old reality star and the 25-year-old rapper. Picture: Andy Kropa, left, and John Salangsang/Invision/AP

The 'Butterfly Effect' hitmaker's partner Kylie Jenner gave birth to the couple's first child on Thursday , February 1, and Travis is overjoyed by the baby's arrival.

He wrote on Twitter: "2.1.18 ... 4 ever ... New rager in town. !!! (sic)"

Messages of support flooded in for the star, with Twitter soon filling with congratulatory messages for the pair.

Kylie took to social media earlier to reveal she had given birth to a baby girl as she explained why she was off social media for so long.

Kylie Jenner announces birth of baby girl, shares pregnancy video

She wrote: "I’m sorry for keeping you in the dark through all the assumptions. 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...Thank you for understanding."

♥️

A post shared by Kylie (@kyliejenner) on

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