"I'm so excited for what the future holds for us if the last four years are anything to go by, we'll have some epic adventures, a few challenges thrown in and a whole lot of love."
"Oh, and one thing the future will definitely include is our first baby, due in September," Matilda added, followed by an eruption of applause from the lovebirds' wedding guests.
The mother-to-be also confirmed that she didn't the baby news a surprise from her new husband.
After a fan asked "did Art know? Or was it a surprise for him too?" Matilda simply replied "he knew!!! Xx".
Others congratulated Matilda for her creative baby reveal, including Kiwi singer Anika Moa who commented: "Best announcement!" alongside a heart and baby bottle emoji.
Millie Elder-Holmes wrote: "This is everything", while celebrity cook Nadia Lim commented, "that's so cool!" on the Instagram post.
In an earlier video, Matilda showed other lovely moments from her and Art's wedding day – which took place last month - including them both getting ready, walking down the aisle and their first dance.
So cute!