The Made In Chelsea star found out her brother Spencer Pratt and his wife Heidi Montag are expecting a baby after she read it in the news.
Speaking exclusively to OK! Online at the launch of her second AW17 French Kiss collection with Goddiva, she said she wasn’t mad about not being told in person.
“They announced it on my birthday online, and my mum emailed me asking if it was true,” she said.
“I called my brother and he said ‘I don’t know how to call you in the UK.’ So I FaceTimed him and I spoke to Heidi and he started crying.”
Speaking about what kind of parents they’ll be, she added: “I’m already an aunt but this will be a completely different experience I am sure. This will be more like a comedy show, not in a bad way.”
The 31 year added: “Heidi is going to be the best mum in the world. She has four little dogs, and she has the fanny pack with four leashes and they all have strollers.
Steph Pratt unveils rock hard abs during her romantic break with Jonny [Instagram]
“She will be such a good mum, but my brother? I can’t even imagine. Heidi runs the house, she does everything.
“I hope him becoming a dad gives us more of a relationship.”
Speaking about her fashion line, Stephanie, who is dating Love Island’s Jonny Mitchell, added: “I always wanted to do a line because I went to fashion school. It’s what I always wanted to do when I was younger but then I fell into The Hills because Lauren [Conrad] was my class mate and my brother was dating Heidi.
“I’ve been offered the chance to do a line before, but a lot of them were just stamping your name on clothes but I didn’t want to do that, I had integrity.
“So it wasn’t until last year that I had a meeting with Goddiva where they said I could creative control. I’ve been involved right from doing the sketches, and it’s been so awesome to work with.
“Goddiva was what I was waiting for, I could have done it ages ago but I wanted to be involved with the designs.”
She continued: “Different body shapes were important to me. I wanted to do a line that was flattering to all, I’m quite square with my shape so I wanted something that anyone can put on and it gives you a body.”
Stephanie Pratt’s new A/W17 collection with Goddiva is out today, September 26. Available to buy at www.goddiva.co.uk