Kourtney Kardashian enjoyed an early birthday celebration on Tuesday (17.04.18).

The 'Keeping Up With the Kardashians' star turned 39 on Wednesday (18.04.18) but marked the occasion a day before with her sisters Kim Kardashian West, Kendall Jenner, and Khloe Kardashian, while visiting the 'Revenge Body' star and her new baby daughter True in Cleveland.

She shared a photo of a pink cake decorated with roses and berries, the words 'Happy birthday Kourtney', and two gold candles on her Instagram Story and wrote: ''It's my birthday tomorrow!! Thank you @khloekardashian (sic)''

And that wasn't the only sweet treat Kourtney - who has children Mason, eight, Penelope, five, and three-year-old Reign with ex-boyfriend Scott Disick - received as she also shared a photo of some colourful mini donuts which spelled out 'Happy Birthday Kourtney'.

The excited star also posted a photo of herself and half-sister Kylie Jenner hugging and laughing at Coachella over the weekend and wrote: ''It's my birthday tomorrow.''

Kourtney is known for her strict diet but she recently admitted she's changed her eating plans as she used to be rigid in her day-to-day life but splurged when on vacation, so she's now decided to be loosen up a little.

She wrote on her app: ''That wasn't making sense for me anymore.

''I don't want to throw my body off by eating whatever I want when I travel and then be really strict other times.''

Meanwhile, after enjoying their celebration with Khloe, the sisters, including Kendall Jenner, have now flown back to Los Angeles following their brief visit.

The 'Revenge Body' star gave birth to her first child with boyfriend Tristan Thompson last week, just days after it was claimed he had been kissing another woman in a club.