Lauren Brant shares the reality of parenting she wasn't expecting.

Even the most well-prepared new mothers will tell you there were parts of motherhood they were not expecting.

TV personality Lauren Brant is no different. The first time mum to one-month-old Miller shared on Instagram on Monday that there was one big thing she got wrong about motherhood – but she was all too happy to be pleasantly surprised.

“When I was young I always used to think that being a parent was such an adult thing, because it is such a huge responsibility to look after and raise a human being so surely that meant you had to be serious all the time?!,” she wrote.

“Nope.”

A post shared by Lauren Brant (@laurenbrant) on Jun 26, 2017 at 4:26am PDT

What the 28-year-old said she found instead was that, if anything, she and her husband Barry Hall were acting a little less serious after the birth of their son in May.

“FYI – when you become a parent, there is NOT, I repeat, there is NOT a switch that gets flicked that makes you ‘grown up’,” she wrote.

“You learn to to love and care like you never have before and you become way less selfish but if anything, it reignites the kid inside you.”

Listen: Why so many parents are at risk of burnout.

“The world is a happier place, it’s as though you see everything through the eyes of your child and it totally makes you realise what moments are to be cherished and what is not important!”

Any non-parents will likely breathe a sigh of relief that being a parent doesn’t mean you have to grow up completely.

What surprised you most about parenthood?