Happy first birthday! Fans got to watch Maddie Brown give birth to her baby son Axel last season on Sister Wives, so it's hard to believe that he's already one year old. Maddie took to Instagram on Sunday, May 20 to share a sweet message to her son Axel — whom she shares with her husband Caleb Brush — in celebration of his first birthday.

"One year ago today I held a brand new little baby boy in my arms that quickly became the center of our worlds! It has been my pleasure and blessing to be his mommy," she wrote in the caption. "I can't believe how quickly the time has gone and that he is already one. I look forward to the many more years of watching him grow."

Fans also can't believe that Axel is already one year old, and they flooded the comments section with their well wishes for the adorable little boy. "Wow time flies! What a sweet family you and Caleb have begun," one fan wrote, and another commented, "Happy [first] birthday handsome boy! You are a lucky boy to be born with so many family members that love you!"

Since Maddie comes from a very large polygamous family — her father Kody Brown has four wives and 18 children — little Axel does have a lot of aunts and uncles and grandmothers that love him. Maddie's mom Janelle Brown was so excited to become a grandmother and she was very hands on with her daughter throughout her pregnancy — and she helped coach Maddie through her grueling 72-hour labor.

So of course, the proud grandma took to Instagram to share a sweet message to her grandson. "Oh my little grandson Axel. I think the sun shines for you. You illuminate my whole life. Happy [first] birthday!" she wrote on in her caption.