Laura also revealed that she and Matty don't know if they'll be having a boy or girl, but she's getting strong "vibes" as to what gender their child will be.
"We don't know if it's a boy or a girl. We're having a surprise," she explained.
"But I'm getting very strong boy vibes, which means absolutely nothing because I also got very strong boy vibes when I had Marlie. So... It's probably a girl."
The jewellery designer also said that despite Marlie and baby number two being 19 months apart, the second pregnancy was "very, very planned."
"We are insane. I'm starting to question whether it was a good idea but it's happening," she joked.
Laura and Matt announced the exciting news that they were expecting their second child back in September on a family holiday to Byron Bay.
Posing on the beach, the family-of-three smiled for the camera with Laura's burgeoning bump on full display.
"I recon we’ve kept this little beach ball under wraps for long enough..... Half way to number 2. A big shout out to @matthewdavidjohnson for his contribution," Laura joked in her caption.
Former Bachelor Matt also shared his own post that showed toddler Marlie with a shocked expression.
"Marlie-Mae learning shocked face couldn’t have been timed any better.. WE’RE HAVING A BABY! Please brace yourself for twice the amount of dad jokes," he captioned the snap.
Soon-to-be parents-of-two Matty and Laura met in 2017 on season five of The Bachelor Australia.
The couple celebrated three years passing since the finale, shortly before their pregnancy announcement was revealed.
"I’ll be honest, we both kinda forgot the finale happened 3 years ago today. I blame the fact that we’re still so disgustingly in love with each other it’s made our memories slightly hazy... and the fact that we’re battling extreme parental fatigue," Matty joked on Instagram.