Demi Moore feared her daughter Rumer wouldn't "make it" through childbirth.

'The Substance' star was by Rumer's side when she delivered her little girl Louetta in a waterbirth at home, and Demi has now admitted she worried about her daughter's pain threshold.

She told PEOPLE magazine: "It was really incredible ... Rumer had a home birth, and there was a moment when I thought: 'Oh boy, I don't know if she's going to make it', like she has a different pain threshold than I do.

"To just see her move into her own power and focus, it was a really extraordinary, beautiful moment."

Rumer, 36, previously admitted she was terrified about giving birth even though she was following the plan she set out to deliver her daughter at home with her loved ones by her side.

During an appearance on the 'Informed Pregnancy' podcast, Rumer explained: "I was sitting with everyone outside, and I was just crying.

"And I was just saying, 'You know ... I don't know if I can do this. And this is the birth that I want. I want to do it at home. But I just don't know if I can do it. It was really a kind of ... It was really a kind of ... psycho spiritual experience ...

[After getting into the birthing tub] ... the contractions were getting really intense, like getting to that point where it's the overwhelming pain. I start moving in the water. Like, I don't know, some sort of sexual mermaid.

"I let go, I actually let myself surrender to ... what was happening. And my body ... just downloaded what to do."

However, Rumer still endured a scary experience as Louetta was born with the umbilical cord wrapped around her neck.

She explained: "My midwife and my partner [Derek Thomas] caught her. It was the wildest thing. She had a cord wrapped around her neck, but it was also wrapped around her body in like almost like a prom sash.

"We had four hands under there, under the birth stool. I'm going, 'Give me the baby. Give the baby' ... But then, as soon as they untangled her, she was in my arms ... [It was] the most ecstatic, joyful moment of my entire life."