Kris Jenner ... posted pregnancy photo for son's 25th birthday (photo: krisjenner.celebuzz.com)

Kris Jenner ... posted pregnancy photo for son's 25th birthday (photo: krisjenner.celebuzz.com)

Hot on the heels of mum-to-be Jessica Simpson posing naked for Elle, Kris Jenner, mum to the Kardashian clan, has released a skin-baring photo of herself when pregnant.

The photo, posted on Jenner’s blog, shows the mum heavily pregnant with son Rob in 1987.

The accompanying text read: “Happy 25th birthday to my wonderful, handsome son, Rob!! Rob, you are the best son a mother could ask for and you make me proud every day. I love you so much!!”

But the public wasn’t as excited to see Jenner in her underpants as she may have imagined. One poster commented, “Kris, it is not all about you. Why would you post such a private picture on your blog for all to see and why on HIS birthday?”

Another blogger wrote, "Because nothing says 'happy birthday' like seeing your mom naked!"

The birthday boy himself has yet to reply to his mum’s public "gift".