Taylor Swift was surprised by a belated 30th birthday party in the recording studio on Wednesday (18.12.19).

The 'You Need to Calm Down' singer reached the milestone age on December 13, but a few days later, her collaborators Jack Antonoff and Laura Sisk hosted a small celebration to mark the occasion.

Taylor shared a photo of herself holding a birthday cake with Jack and Laura holding balloons either side of her and wrote: ''Walked into the studio to a surprise birthday party from these two @jackantonoff & @sharp_stick - it's equally wild and cozy to think it was the three of us in a room making a song called Lover here last year. [heart emoji].''

The 'Cats' actress had marked her birthday with an ''aggressive'' festive-themed party with friends including Jack, Ryan Reynolds, Blake Lively, Martha Hunt, Camila Cabello, Halsey and Gigi Hadid - with a festive-themed bash, which took place after she'd performed at the Z100 Jingle Ball in New York.

She wrote on Instagram: ''Honestly spending my 30th with the fans who have made my life what it is at jingle ball, then throwing the most aggressive holiday party known to womankind ... I just seriously feel so lucky for you all and will spend forever trying to find ways to say thank you. *cries in Christmas tree* (sic)''

Taylor previously admitted she is approaching her thirties with a healthier outlook.

Speaking before her birthday, she said: ''I'm really excited about it. I've heard really good things about your thirties. Feeling a bit more secure ... a bit.''

And the 'Me' singer believes her age has helped her to analyse ''toxic messages'' about her body and improve her relationship with body positivity.

She added: ''One thing going into my thirties that I'm really stoked about is I now can really recognise and diagnose toxic messages being sent to me by society, by culture about my body. I'm a woman, I'm not a coat hanger. I need to feel healthy in my life, and I need to take pleasure in food, and I need to not use my body as an exercise of control when I feel out of control in my life.''