Kate Upton says things are ''heating up'' as she shares her first swimsuit pictures after giving birth.

The 26-year-old model welcomed her daughter Genevieve - whom she has with husband Justin Verlander - into the world seven months ago, and is already showing off her toned post-pregnancy body as she took to Instagram to model a swimsuit in a sizzling new photo.

She captioned the photo: ''Things are finally heating up'' alongside a fire emoji.

And many of her celebrity pals agreed with her, with some even joking that she must have used a surrogate mother to carry her daughter because of how toned her body looks already.

Fellow model Lily Aldridge commented: ''Hot mama'' alongside several fire emojis, whilst comedian Whitney Cummings added: ''Now I'm starting to get suspicious you had a surrogate.''

Kate even received praise on the image from her baseball pitcher spouse, who agreed with Lily and called his wife ''One hot momma!'' alongside two emojis with hearts for eyes.

The model is no stranger to swimsuits, having graced the cover of the Sports Illustrated Swimsuit issue three times, but recently said modelling swimwear has been ''tough'' for her because of the ''criticism'' she faced over her body.

She said: ''When I first came out on the cover of Sports Illustrated, I had a of criticism on my body and it was a really tough time. One of the hardest moments was when a blogger really attacked me and my body calling me these mean names and it really hurt me and upset me. And I was like, 'Why am I even doing this? Why am I evening putting myself out there to get this scrutiny?'''

But Kate was inspired to keep pushing forward with her career when her manager showed her a slew of fan mail that had been sent to her from women who were also struggling with their body image.

She added: ''There was all of this fan mail of women expressing to me their different stories - how they suffered from body image issues or eating disorders. And I was like, 'That's why I'm doing it. It's for them.' And it's for me too. It's for me to love myself again and find that happy place again. It's so hard the criticism we face, on Instagram and seeing everyone at their best all the time on social media. How do we become our best self? Why are we working out? It's for us. It's for us to live our best life. To be the best mums. The best business women. Whatever it is.''