They grow up so fast! The (second) littlest member of the Little People, Big World family is coming up on his first birthday, and he's already changed so much. Although proud mama, Tori Roloff, 26, posts updates about her son every month, she took to Instagram Stories over the weekend to reveal he's now going through a growth spurt.

"I think someone is going through a growth spurt," she captioned the photo of Baby J sleeping. She added the timestamp, "8:21 a.m."

jackson roloff growth spurt

Yet this isn't the first time the mother-of-one posted a photo on Instagram about Jackson's growth. Back in August, she wrote, "I think we're going through a growth spurt" on a photo of her then three-month-old.

As previously reported, Jackson has achondroplasia (which is the same form of dwarfism that dad Zach has), but the new parents said they were ready to take on all the parenting challenges that come with raising a child that may be considered "different." In July, Zach told People, "You have to encourage a dwarf child a little more because it will take them five steps to do what others can do in two. But I knew, dwarf or not, I was going to parent my child with the mentality that not everyone gets a trophy." The 27-year-old added, "The world is changing. People are more open to diversity. Whatever he wants to do, we’re going to find a way to help him do it. That’s our job in life now."

jackson roloff growth spurt

Recently, the reality star sparked rumors she was expecting baby No. 2 — based on the way she was standing. No, we're not joking! She shared a photo slamming her haters, but all people could focus on was her pose. "What does this pose mean? Hiding a baby bump?" someone wrote. Although she hasn't commented on the rumors, we certainly hope it's true. Baby J would make the best big brother!

Little people, Big World returns Tuesday, April 3 at 9 p.m. EST on TLC.

Scroll through the gallery below for more photos of baby Jackson!