Paltrow posted a sneak peek of her upcoming part in Glee on Instagram two days ago.

The actress, who has most-recently starred as Pepper Potts in the Iron Man series and The Avengers, explained the challenges of maintaining a work-life balance in an acting career.

"I think it's different when you have an office job, because it's routine and, you know, you can do all the stuff in the morning and then you come home in the evening," she said. "When you're shooting a movie, they're like, 'We need you to go to Wisconsin for two weeks,' and then you work 14 hours a day and that part of it is very difficult. I think to have a regular job and be a mom is not as, of course there are challenges, but it's not like being on set."

"It's much harder for me," she said. "I feel like I set it up in a way that makes it difficult because…for me, like if I miss a school run, they are like, 'Where were you?'"

Paltrow won an Oscar for her lead role in Shakespeare in Love in 1998 and starred in a host of other films thereafter, from Shallow Hal to The Talented Mr. Ripley. She is to star alongside Johnny Depp in upcoming film Mortdecai, which is based on a series of novels about an art dealer who searches for stolen paintings.

Gwyneth Paltrow is to quit acting