Heidi Montag is a "total mess" after her son Gunner turned one year old.

Heidi Montag's Instagram (c) post

Heidi Montag's Instagram (c) post

The 32-year-old reality star and her husband Spencer Pratt celebrated the first birthday of their son Gunner Stone on Monday (01.10.18), and in an emotional post on her Instagram Story, Heidi has admitted she found the important milestone "emotional".

In a video which showed the blonde beauty wiping away tears, she said: "I decided not to wear makeup today because I'm a total mess. God, it's so amazing. Gunner is just such a blessing and I can't believe that it's already been a year. Wow, what a day.

"It's been the most amazing and most challenging year of my entire life. It's just been so great, every moment. I can't believe he's already 1! ... Bit emotional today, it's a big day. And I'm just really thankful. I hope you guys are all having a great day. And I'm just going to sit here crying."

Gunner had an exciting day to celebrate his special day, with his 35-year-old father taking him for something to eat at Palisades Village in Pacific Palisades, California, where the tot enjoyed his first French fry, fruit sorbet and a "Happy Birthday" song from his parents.

The youngster also received a whole host of lavish gifts, including Gucci attire and some 'Reputation Tour' merchandise from Taylor Swift.

Heidi also re-posted a series of images from when she gave birth to Gunner, including one where she thanked the tot for "making [her] into a mom".

The 'Hills' alum wrote: "Thanks for making me into a mom @gunnerpratt ! I am a very different mom than I had imagined. You never know until your in it... this has been the most amazing and challenging year of my life. I will give it my all! I am sure I will fall short and continue to face challenges but I pray for strength, wisdom, and help. So excited to be Gunner's mom! (sic)"