The 26-year-old posted the most honest photo of motherhood that we’re sure the photo sharing site has ever seen.
Here it is – WARNING – it requires a strong stomach and may (definitely) contain a lot of baby poop.
Cartwright captioned the photo with, "Just when you think you're safe... they poop in your hand, on the floor and your clothes."
Her two-week-old son, Max William Miller, hadn't quite finished his business when mum picked him up. Next minute - a somewhat yellow explosion happened all over mum. Oops.
See Kelly Cartwright talk about her success as a Paralympian. Post continues after the video...
One commenter said, "[my son] pissed and pooped on Michael the first day. It was great."
Another said, "I still remember that time with Peytan when she was a newborn."
We've been seeing a lot of photos of the gorgeous Max. Cartwright and her little family are absolutely adorable and seem very happy.
She was a contestant on Dancing With the Stars mid last year, and while she didn't win she was a delight to watch. Cartwright and her husband, William Miller welcomed their baby boy into the world at the beginning of January this year.
With her first awkward parenting moment tackled, we can't wait for the next chapter in Cartwright's motherhood journey.
What's the first hurdle you had to get over with your baby?