Hailey Bieber is set to become an aunt, as her sister Alaia Baldwin is pregnant.

The 27-year-old daughter of Stephen and Kennya Baldwin is expecting her first child with her husband Andrew Aronow, making her model sister Hailey - who is married to Justin Bieber - a first time aunt.

Alaia announced the news on Instagram where she posted a picture of Andrew kissing her baby bump, as she also revealed she's having a baby girl.

She wrote alongside the image: ''I made something extra special for @andrewaronow's birthday this year..... #BABYARONOW coming to ya August 2020 #it'sagirl #happybirthday and #yourewelcome (sic)''

And Hailey, 23, couldn't contain her excitement as she took to the comments to express her joy at becoming an aunt in just a few months' time.

She wrote: ''My niece

''Screaming!!!! (sic)''

Hailey also shared Alaia's post on her own Instagram Story, where she wrote: ''I'm gonna be an Aunty!!!!!! (sic)''

The happy news comes as Hailey previously revealed she would love to have children of her own some day, but insisted she wouldn't be considering it ''any time soon''.

She said in 2018, just months after marrying Justin Bieber: ''I love kids and I can't wait to have my own. I would say that now, that's a closer reality, but definitely not anytime soon.''

The 26-year-old singer echoed those sentiments in his own recent interview.

Justin said: ''I want to start my own family in due time. I want to enjoy being married for a little bit, go on tour, be married, enjoy traveling with just us, build more of our relationship. I think that it's definitely the next step, for sure.''

And when it comes to how many kids he wants, the 'Yummy' hitmaker wants to let Hailey decide.

He insisted: ''I think it's up to Hailey because it's her body.''