The Texas natives are already parents to two sons, 12-year-old Drake and 9-year-old Duke, and two daughters, 11-year-old Ella and 7-year-old Emmie Kay.
The soon-to-be Gaines won't be the only little one running around Waco! Joanna's younger sister, Mary Kay McCall -- whose home renovation was featured on Tuesday night's episode of Fixer Upper -- is expecting her sixth child as well.
Chip and Joanna announced in September that they would be ending their extremely popular HGTV show after its fifth season, in part to spend more time with their kids. One month later, they told ET that it was not because Joanna was pregnant, however.
"There's so many [rumors], even leading up to it -- I had this skincare line, so I'm leaving. It made it look like I was doing my own thing and Chip didn't even know about it. That was just a big rumor," Joanna told ET's Kevin Frazier. "That our marriage is on the rocks... I was pregnant. It's funny when you start hearing this stuff. I was like, 'I guess people can just make stuff up.'"
According to Chip's possibly TMI tweet after both the Instagram post and the pregnancy reveal on Tuesday's episode of Fixer Upper, the fifth-time parents-to-be may not have known they were pregnant when they spoke to ET back in mid-October. According to Chip's social media post, their fifth pregnancy can be traced back to JOHNNYSWIM's Oct. 12 concert in Waco.
"...They put on a little too romantic of a concert.. anyways, one thing led to another, & we are officially pregnant. And I could not be more EXCITED! #5 #7ThePerfectNumber," Chip wrote in part, to which the band adorably responded, "We do what we can!"