Lindsay also posted family photos in her hospital room on Thursday, April 4.
"Baby girl is here and we are so in love," Lindsay gushed.
"Mama and baby are healthy and we are soaking up every minute with our little piece of Heaven. Thank you for all the love we will share more soon. #birth #babygirl #laboranddelivery #csection #birthannouncement."
Lindsay had updated fans on her labor and delivery in the hours before her daughter arrived.
"Soooo we are heading to the hospital! Contractions are in full effect and about 2-3 min apart," Lindsay wrote via Instagram Stories on Wednesday.
The new baby joins Lindsay and Sam's first-born child, Sage Jill, a two-year-old who was born in November 2020.
Lindsay recently reflected on her second pregnancy when she was 38 weeks along.
"As this pregnancy is coming to an end, I am just feeling so grateful for this body of mine that has kept our baby girl growing and safe and that it has allowed me to still move and stay active + chase after our little Sagey," Lindsay shared via Instagram.
"can't believe we are so close to having baby girl with us."
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Lindsay also wrote a sweet tribute to Sage in an April post, writing, "I have been feeling all the emotions as we get closer and closer to becoming a family of four. It's crazy to think that there will be another baby girl in our family and I can't quite wrap my head around how my heart is going to handle doubling in size again when she arrives but I know that it will and I'm so excited."
"We are beyond grateful and blessed for the time we have had with Sage as our little fam of 3 and we are all so excited and ready to have baby sister join our family so soon," she continued.
"My heart literally explodes when I think about seeing Sage with her baby sister for the first time."
"We are beyond grateful and feel so blessed to be adding a new addition to our family," Lindsay wrote on Instagram.
She later added, "You guys this is literally the best thing in the world, to be able to able to tell you all our amazing news. It's been our little secret for a while."
The pro dancer and choreographer then revealed in early November that she had a baby girl on the way. She and her husband hosted a gender-reveal party at their Utah home.
"We are beyond excited to bring another sweet girl into our family and so so happy that Sage will have a sister," Lindsay gushed.
Lindsay later reflected on her pregnancy via Instagram Stories, telling her followers, "You guys, we are having another girl!... I obviously would've been happy with either a boy or a girl, I would be stoked, but I am so excited that Sage is going to have a little sister."
"I can't imagine a life without sisters, so I'm so grateful that they will have each other. It's so crazy -- I'm going to have two little girls!" she added.
Lindsay had struggled to conceive her second child, which she was open about with her followers on Instagram.
Lindsay revealed in a YouTube video in October how she and Sam started trying for another baby in January 2022, which she acknowledged was not a very long time compared to other couples out there.
"Month 9, I get a faint positive test. It was very faint... I was also testing way early... and then literally every day after that was negative," Lindsay said in the YouTube video.
Lindsay shared how she could've had a chemical pregnancy or a false positive, which is rare.
"It was awful because I got so excited. I was so pumped out of my mind and told Sam... and it was super disappointing to have all that [taken away]," Lindsay said.
But the following month, Lindsay discovered she was pregnant again.
"I thought I had it hard, but I know other people have it so much worse," Lindsay noted.
"Doing what is best for my daughter is always going to be at the top of my list!" Lindsay wrote on Instagram before the Disney+ season premiered in September.
"As many of you know, my family and I live in UT and in order to do DWTS I have to move myself and my daughter Sage out to LA and leave behind my husband Sam who works full time here in Utah."
She elaborated, "And there is a lot of sacrifice that has to be made that unfortunately just did not feel right for us this time around. We exhausted every option we could think of to make it work but at the end of the day, none of the options felt good in my heart or felt like the right thing for our lives right now."
Lindsay also confirmed at the time how she and Sam were trying for their second child.
"We are also trying to grow our family and that in itself is a complicated logistical thing as I'm sure many of you understand," Lindsay wrote.
"All this being said it's so important to me that you understand none of this has anything to do with my love for the show as that will NEVER change and it also doesn't mean that this is the end for me and DWTS."
"Although this decision has been so hard to make," she added, "I feel so much peace about it and know that it is the right thing to do."
Lindsay announced she was pregnant with her first child in May 2020, just one month before she and Samuel celebrated five years of marriage.
Lindsay and Samuel were high school sweethearts who tied the knot at the Salt Lake Temple in Salt Lake City, UT, in June 2015. Approximately 150 guests reportedly attended their reception at the Sleepy Ridge estate.