"November 20th 2:02am @astridloch made my dreams come true," Kevin, 37, wrote on Instagram the day after his baby's arrival.
Kevin added of Astrid, "She is my absolute hero for everything she went through the last 2 days in the hospital, and the last 2 years doing everything it took to get this perfect munchkin into the @thewendtgang. [Heart emoji]. I never thought a love like this existed."
Astrid also took to Instagram on Sunday and uploaded a picture of her little baby's hand.
"My whole world. Born 11/20/2021 & finally home with the rest of the @thewendtgang," Astrid wrote alongside the image.
"Sorry to keep you all waiting, just had to soak this moment up for ourselves first. #babywendt #ivf #ivfbaby #infertility."
Last week, Astrid, who met Kevin on Season 5 of Bachelor in Paradise in 2018, posted photos of their baby's blue, gray and white nursery.
"After meeting on the beach it was only right to create a little nautical dream space for our little beach babe. Can't wait to meet baby w and bring him or her home," Astrid captioned the slideshow, calling the new room her "favorite" in the house.
Astrid and Kevin announced they were expecting Baby No. 1 in May by posting photos of themselves holding up ultrasound photos.
"One of the first conversations @kevin.c.wendt and I had was about how we both loved kids and couldn't wait to have our own. When I think about Kev holding our little angel for the first time my heart flutters. Even in my wildest dreams I couldn't have imagined how amazing this would all feel."
Astrid then provided a message to all of the couples out there trying to get pregnant.
"My heart is with you. We know first hand how hard it can be to see these kinds of posts and feel sad & discouraged. We too struggled with fertility and conceiving naturally -- it's the toughest thing we've ever been through and I can't wait to share more of how we got here," Astrid continued.
"But today is finally about some good news & we hope you can enjoy it with us. #babywendt #ivf #infertility #infertilityawareness."
And Kevin wished Astrid, his "queen," a "Happy 1st Mother's Day" at the time.
"This is a very big day for us, after a long and tough road to get here. The @thewendtgang is officially growing!! Thank you @astridloch for giving me the one thing I've wanted most in my life," Kevin gushed on social media.
"#ivfbaby #ivf #ivfjourney #ivfawarness We will have much more to share about the struggle and steps we took to get here, but today we are just so excited to share the news that we are going to be parents!!"
After the couple spent a year trying to conceive a baby naturally, Astrid underwent multiple intrauterine inseminations and then started IVF a week before Christmas in December 2020.
Astrid ended up going through two rounds of IVF before getting pregnant, according to People.
"IVF is just so much more intrusive, so we were trying to go that route at first and then during our second cycle, we actually ended up having an ectopic pregnancy... I ended up having to take medication to terminate the ectopic pregnancy, and then it pushed our whole thing back another two-and-a-half months," Astrid told the magazine in May.
Astrid recalled the IVF process being "time consuming," a bit overwhelming, and "really hard on the body," as she had to visit the clinic two to three times a week amid the ongoing coronavirus pandemic.
"We spent a lot of nights in tears because we just didn't understand why it wasn't working for us," Kevin admitted.
"You can't try [to conceive] after that because the meds that you take to terminate are so strong. It's basically like a cancer med that they give you to terminate all living cells. So then, we couldn't try and go into our IVF cycle for almost three months."
The couple also announced at the time they wanted to keep the baby's gender a surprise until his or her November birth.
Astrid revealed via Instagram in June that she was battling "typical nausea, exhaustion and weird food aversions/cravings." She also said she wasn't getting good sleep due to her "sore" butt from her "strict protocol of injections."
But once the couple discovered Astrid was pregnant, they decided to delay their wedding once again, probably for a full year.
The couple's little bundle of joy was due only day before Astrid and Kevin's rescheduled wedding date this month, People previously reported.
Astrid and Kevin were a solid couple on Bachelor in Paradise in Summer 2018, but Kevin blindsided and dumped Astrid before the Fantasy Suite dates and ended up trying to win her back during the live reunion show.
Kevin explained on the reunion special of Bachelor in Paradise's fifth season he had a lot of fears and insecurities he had to deal with via therapy regarding his previous romances before being able to commit to a woman wholeheartedly and settle down.
One of Kevin's exes is Ashley Iaconetti, whom he met on The Bachelor Winter Games but split from in March 2018.
"I will never forget when I left the show, going to my best friends and being like, 'I know we technically broke up on the show, but I'm pretty sure this is the person I'm going to marry,'" Astrid had told People.
"I feel like I knew right away how well he fit into my life."
Back in November 2018, Astrid and Kevin's families reportedly met each other at an event in Toronto, Canada, and then the following month, Astrid -- who worked as a plastic surgery office manager in Tampa, FL -- moved in with Kevin in his hometown of Toronto.
Prior to appearing on Paradise several years ago, Astrid competed to win Nick Viall's heart on The Bachelor's 21st season, and Kevin found fame when he won the first season of The Bachelorette Canada.