Tia shared during a recent episode of her "Click Bait with Bachelor Nation" podcast, "We technically were pregnant when we got engaged, we just didn't know... I remember perfectly [when we conceived]. It was March 26 and we were about to go watch the Razorbacks play basketball. It was March Madness."
Tia -- who joked about the afternoon sexual encounter being "pretty fast" so she could get a spray tan and eat Chipotle -- told her podcast co-hosts Joe Amabile and Natasha Parker that she was totally shocked about the baby news.
"I wasn't excited at first. I was freaking out," Tia confessed.
"I was like, 'You are kidding me?! I'm trying to plan the wedding of my dreams.' At this point, I was still trying to [get married] within six months -- getting it done this Fall. And I just could not believe it. At this point, I'm 30."
Tia said she and Taylor "weren't trying to get pregnant," but at the same time, they "weren't trying very hard not to get pregnant."
Tia recalled being "excited" once she got over the initial shock of her baby and arrived at the conclusion she and Taylor will not have a 2022 wedding.
"I think that was kind of the bummer part," Tia said.
Tia announced she's expecting her first child on Father's Day by posting a sweet tribute to her late father as well as her fiance.
"While I wish I could tell my dad all the good news in person, it brings me peace that he knows about it long before I do... I have no doubt my dad had a hand in this," Tia captioned a black-and-white image of the couple embracing her small baby bump.
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She added, "Happy heavenly Father's Day to the first man I ever loved and Happy soon-to-be Father's Day to my forever."
Unfortunately, Tia's post "disappeared after an hour" and so she had to upload the announcement again the following day.
"I cried for three hours... I had spent all afternoon typing that out," Tia said with a laugh, adding, "It's only the biggest news of my life and it disappeared! People thought, 'Just kidding, she's not pregnant.'"
Tia said she actually "felt totally normal" before taking her first pregnancy test. She was a little late on her period but just thought that was from the stress of wedding planning.
However, Tia shared with Joe and Natasha how she actually had a dream that she was pregnant before receiving the confirmation
"I had a dream that I was pregnant. Then I had another dream that I found out I lost a baby. I was like, 'Holy sh-t, what a freakin' mind f-ck," Tia explained.
The next day, Tia texted her friend to dish about the pregnancy dream, and she was like, 'Aren't you late on your period?... You should take a test.'"
Tia listened to her friend's advice and took a test, and it gave her a positive result.
Tia said she took "at least four" pregnancy tests and a blood test before sharing the big news with Taylor.
"I knew I wanted to tell [Taylor] in person and I knew I wasn't going to be able to wait until he got off work, so I asked him, 'Hey, do you want to grab lunch today?' He was already going with some of his friends, so I went, 'Sh-t!' So we just went to lunch," Tia recalled.
Tia said she was so nervous that she "wasn't going to be able to eat" unless she told him.
Tia therefore told Taylor that she's pregnant while she was sitting in her car outside the restaurant. Taylor apparently played it cool and then the couple enjoyed a meal with his friends, whom Tia playfully called "idiots."
"Taylor's reaction was fine. He wasn't bummed or anything... He was like, 'Sounds good!'" Tia explained.
Tia and Taylor's baby is due in December 2022, but they have yet to find out their little bundle of joy's sex.
But Tia said that she'd like to honor her late father with her name choice if she ends up having a son.
Tia and Taylor got engaged during a "Bachelor Live On Stage" performance in April in Atlanta, GA, and they currently live in Nashville, TN, together.
Tia said she had "never been more shocked" than in the moment when Taylor popped the question onstage.
"I did not expect it, not one freakin' little second," Tia noted.
Tia and Taylor were only together for nine months, officially, before they got engaged.
"But we've known each other [as friends] for over a year," Tia said after the engagement. "I know people are like, 'It's so fast,' but I'm 30! He's 26. At this point, we don't have to wait... And in Bachelor Nation, it's an eternity!"
When Tia announced her engagement on Instagram, she captioned a selfie, "Never been more shocked or sure in my life. I love you so much Tay, my FIANCE!!!"