Julia Roberts refuses to swear in front of her children.

The 'August: Osage County' star, who has nine-year-old twins, Hazel and Phinnaeus, and son, Henry, six, with her husband, DANNY MODER, has revealed she never uses bad language anymore after making the mistake once.

The 46-year-old actress told People.com: ''In the nine years of being a mother, I've only done that one time, and it brought all of us to a screeching halt. Everyone was like, 'What just happened?' It was horrible! I still think about it now, and I still can't believe I did that. The children just stopped, and I said, 'I am very sorry!' ''

She added: ''It was a traffic thing. Somebody cut me off, and I was like, 'f**k!' It was dangerous. The children and I could have been hurt. Then I told them, 'Mommy is so sorry,' and we all just kept on going. We all recovered!''

The Golden Globe nominee insisted she and her family are too happy to use negative language.

She said: ''Our conversations are so much happier than that. I ask, 'How's school? Who has homework?' It's easy.''

Meanwhile, the actress has also addressed rumours that she is expecting her fourth child after she stepped out in Los Angeles with a noticeable bump concealed by a baggy sweater last weekend.

Asked if there was any chance of her expanding her family, Julia told 'The Late Show with David Letterman' on Thursday night (12.12.13): ''No.''