Julia Roberts celebrates son Henry's 18th

Julia Roberts has shared a sweet message to celebrate her son Henry on his 18th birthday.

The Pretty Woman star marked her and Danny Moder's youngest son's big day with birthday wishes and throwback pic of him as a young child.

"In the blink of a joyful eye, this beacon of a boy is 18," Roberts wrote on Instagram alongside a photo of Henry rocking a green hoodie. "I love you Henry."

Henry's big birthday was also marked by some of his mum's friends. Jennifer Aniston wrote in the comments, "Happy Birthday sweet Henry!"

Rita Wilson added, "Henry! Happy Birthday!"

While Roberts and Moder have largely kept their family out of the spotlight, Moder recently shared a glimpse of Henry and his older twin siblings Hazel and Phinnaeus, 20, while celebrating his Oscar-winning wife on US Mother's Day.

"Mothers make the coolest stuff," Danny wrote alongside a photo of Julia and their trio on Instagram on 11 May. "Love these guys."

Roberts recently gave insight into life as a mum of adults, admitting that her parenting style hasn't changed much since her older two left home.

"I parent them the same way out of the house that I parented them in the house," she told Today, "which is, you know, 'Are you getting enough sleep?' And, 'You sound like you're sick.' And 'Are you drinking tea?' And 'Text me when you get home.'"