Broadway star who played Anna in "Frozen," Patti Murin, shared a photo of her baby girl dressed as Captain Marvel and revealing how her little hero has survived open-heart surgery at 10 weeks old.

She wrote on her Instagram post that her daughter, Cecily, recently underwent open-heart surgery. She revealed that her baby was born with a rather large hole that the operation aims to repair. And while a lot of babies are born with it, many of them close up on their own.

"Preparing for it mentally is 'gut-wrenching at best.'"

She said that they found out about it when she was 22 weeks pregnant. While they had known beforehand that it was inevitable, mentally preparing about it is "gut-wrenching at best." This especially true when she had to see her tiny new daughter go through such an incredibly serious and invasive procedure.

She continued on saying that helping her little girl recover "day by day, breath by breath" has a humbling and inspiring experience for her. She couldn't help but feel proud of her 4-month-old daughter who she said is already "more badass" than she could ever be.

Murin and her husband, Colin Donnell, 38, welcomed Cecily in early July this year. She previously told PEOPLE that she is head over heels in love with her newborn. Parenthood, she said, is already the most insane and beautiful thing in existence. After five years of marriage, the couple first broke the news in February that they are going to parents to a baby girl.

Doing "Frozen" made her want to have a baby girl

Three years ago, Murin learned that she was pregnant while she was auditioning for "Frozen" but had a miscarriage at eight weeks. She said that Frozen reminded her about the importance of family and that it helped her get ready for motherhood.

She added that doing Frozen and building a relationship with fellow actors, especially the young actresses who played Anna and Elsa, made her want to have a little girl of her own. She obviously wants a happy and healthy baby, she said, but the years she spent with Frozen made her want to have a baby girl "real bad."

However, in April, she revealed that she had symptoms of the coronavirus including a cough that made her feel that her head is splitting open from the inside out. Luckily, the baby was okay. She assured her followers that the virus can't cross the placenta making her uterus literally the "safest place" for her baby girl.

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For her first Halloween, Cecily is Captain Marvel because she’s a real life, true superhero. Almost 6 weeks ago, at just 10 weeks old, Cecily had open heart surgery to repair a rather large hole that she was born with. A lot of babies are born with this condition, but the majority of them close up on their own. We found out about this when I was 22 weeks pregnant, so we’d known for a while that this was inevitable. But no matter how much you prepare mentally, watching your impossibly tiny new daughter go through an incredibly serious and invasive surgery is gut wrenching at best. And helping her recover day by day, breath by breath, has been humbling and inspiring. Our daughter isn’t even 4 months old and she’s already more badass than I’ll ever be. What was so difficult for me and. @colindonnell was made slightly less difficult by all of the phenomenal humans at @mountsinaipediatrics. Her surgeon, anesthesiologists, cardiology team, nurses, nurse practitioners, support staff, security guards, physician’s assistants, I could go on and on about every person who helped us along that terrifying path. I have never felt so supported and taken care of, and I was able to sleep at night knowing that she was in the very best hands there are. There is no way to adequately thank the people who have quite literally saved your child’s life, but we won’t stop trying. Also? They have THERAPY DOGS through @mountsinai_pawsandplay as part of their program. As soon as I saw that, I knew we were in the right place. She is doing so, so well now. She’s the most heroic person I know, and I can’t wait to tell her stories about how brave she was when she was just a teeny bean. “Life is not the things that we do, it’s who we’re doing them with.” A post shared by Pattimurin (@pattimurin) on Oct 31, 2020 at 3:13pm PDT

Further in her Instagram update, she thanked the medical staff at Mount Sinai Kravis Children's Hospital who she said made things slightly less difficult for her. She particularly mentioned Cecily's surgeon, anesthesiologists, cardiology team, nurses, nurse practitioners, support staff, security guards, and physician's assistants.

Cecily is doing well now. Murin said that her daughter is the most heroic person she knows. She adds that she can't wait to tell her stories about how brave she was.