Justin Bieber's girlfriend Selena Gomez revealed on Friday that she is expecting to be a big sister soon, as her mother, Mandy Teefy, is pregnant.

Gomez shared the news with her Twitter fans on Friday.

Momma and Brian are finally letting me share the news... My mommys carrying my baby brother or sister :) I'm the happiest girl in the world! Gomez's tweet read.

According to E! News, Mandy Teefy, 35, and Gomez's biological father divorced when she was five years old. Mandy Teefy married her current husband, Brian, in 2006.

The singer also shared a photograph of her pregnant mom and her stepfather when she announced the news to fans.

While Gomez's baby news may be a welcomed one, for her boyfriend Bieber it may not be the same. He has been accused of fathering a child with a 20-year-old woman name Mariah Yeater.

Yeater allegedly filed a paternity suit against Bieber, claiming he is the father of her three-month-old son. She claimed they hooked up at one of Bieber's concert in Los Angeles.

Bieber, 17, and his legal team have disputed those claims and the singer took a paternity test last Friday in order to shut down the rumors. The singer is now waiting for Yeater to provide the DNA sample for her son, Trystan, which is yet to be provided, TMZ reported.

Despite these rumors, Gomez and Bieber are still going strong.