Hayden was speaking to fellow mum and Good Morning America presenter Lara Spencer.
"You know what it's like," she said. "As long as your kids are healthy and happy and all good, I mean, it's fabulous. It's fabulous!"
CLICK ON PHOTOS FOR FULL GALLERY
Hayden Panettiere gave birth to her daughter in December
Hayden added that motherhood had shifted her priorities, and that her sole focus is her daughter Kaya, whom she welcomed with her fiancé Wladimir Klitschko.
"You just reprioritise, and you hear that they're healthy and you don't care about yourself anymore," the actress explained. "I mean, it's the most out of body experience where you go, 'I will completely lay myself on the line for my child,' without even a hesitation."
The 25-year-old actress said that her baby Kaya had become her main priority
Hayden, 25, and Wladimir, 39, announced the birth of their daughter on 9 December, releasing a statement in which they said they were "madly in love" with their baby girl and "over the moon".
The Ukrainian professional boxer has previously echoed his fiancée's feelings, telling E! News: "You don't know what love is until you have your first baby, then you know what love is."
Hayden has also spoken about her new arrival, who weighed a healthy 7 lbs., 14 oz., and measured 20 inches when she was born.
Wladimir Klitschko and Hayden Panettiere got engaged in 2013
"She's really so sweet," the Nashville star told People. "I'm sure that's the way it's meant to be, because when they are putting you through the ringer you're like, 'You are lucky you're so cute!'"
The star added, "You're suddenly looking at this little thing, like, 'Oh, that was you in my belly this whole time.'"
Hayden and Wladimir first met through mutual friends in 2009 and started dating soon after. The couple were together for three years and briefly split due to conflicting work schedules.
In April 2013 Hayden confirmed in an interview that the romance was back on, and she announced her engagement, which had been rumoured since the summer, in October of that year.