Gwyneth Paltrow paid an emotional tribute to her daughter Apple as she celebrated her 18th birthday

Gwyneth wrote on the image-sharing platform: "18. I'm a bit of a loss for words this morning. I could not be more proud of the woman you are.

"You are everything I could have dreamed of and so much more. Proud doesn't cover it, my heart swells with feelings I can't put in to words."

The Goop founder continued: "You are deeply extraordinary in every way.

Happy birthday my darling girl. I hope you know how special you are, and how much light you have brought to all who are lucky enough to know you.

Especially me.

"I say it all the time and I will never stop... in the words of auntie Drew, I was born the day you were born. I love you. Mama."

Gwyneth, who shares Apple with former husband and Coldplay frontman Chris Martin, recently explained how she "fell in love" with her daughter's unusual name and couldn't imagine calling her anything else after Chris first suggested it.

She said: "Her dad came up with the name and I fell in love with it. I thought it was original and cool.

"I can't imagine her being called anything else."

The 'Iron Man' actress also confessed that she makes a lot of mistakes as a parent.

Gwyneth, who also has 16-year-old son Moses with Chris and is now married to Brad Falchuk, said: "I spend a lot of time with them talking and watching. I read this quote. I think it was attributed to Banksy, the artist, who said something like 'This generation of parents will do anything for our kids, anything'.

"Like, we will do anything for our kids except let them be who they actually are. And I read it, and I was like, I had chills, and I thought, 'God,' there are aspects of me that think, 'Well, you should do it this way because, like, that worked for me,' or 'Let's avoid this'.

"And so I just tried to be really conscious of letting them emerge as who they are and being loving and supporting, and I f*** it up all the time, you know? Like, I say the wrong thing. And especially right now because [Apple is] 17. Everything I say is wrong."