"Every time we get an ultrasound she's incredibly energetic and always moving around", Bindi continued.
"She's now about the same size as a mountain pygmy-possum. Too cute!" she added with a love-heart emoji.
Bindi and husband Chandler, 23, are expecting their first child together next year.
The newlyweds tied the knot on March 25, in a spontaneous ceremony at Australia Zoo, right before the Covid-19 lockdown.
In August, Bindi and Chandler posed with a tiny khaki T-shirt to reveal the exciting baby news on Instagram.
"It's an honour to share this special moment in our lives with you. Though I'm still in my first trimester, we really want you to be part of our journey from the beginning of this new life chapter," she told her followers.
"We couldn't wait to share the news as this beautiful little being has become the most important part of our lives. Your support means the world to us.
"Please let me know your best advice and send good vibes and prayers to our little sweetheart. Love and light."
In September, she revealed the gender to her fans.
Posing alongside Chandler and an ultrasound of their baby Bindi wrote: "Our beautiful daughter is now about the same size as a hatchling Aldabra tortoise and is as healthy as can be. We can't wait for her arrival next year."
"I can't wait to meet my niece!" Bindi's younger brother Robert commented, while Chandler also wrote: "I love you and our daughter more than anything."
Plenty of commenters were soon suggesting a name that would pay tribute to Bindi's father Steve Irwin, who tragically died in 2006 in a stingray attack.
"A girl named Stevie, perhaps?" one person wrote, while another commented: "Name her Stevie!"
