Katherine Heigl on Giving Birth to Son Joshua: 'I Actually Prefer the Adoption Way'

Katherine Heigl gets real on the experience of giving birth.

Katherine Heigl definitely experienced the ups and downs of pregnancy with her newborn son, Joshua.

The 38-year-old actress is opening up about her what it was like giving birth, after adopting her two daughters, 8-year-old Naleigh and 4-year-old Adalaide, in 2009 and 2012 respectively. Heigl and her husband, musician Josh Kelley, welcomed their baby boy on Dec. 20.

"[I've had] emotional highs and lows," Heigl candidly tells People. "One minute you're weirdly obsessed with this baby, like 'Don’t take him out of my sight,' and the next you're kind of blue, you're a little sad and a little freaked out."

WATCH: Katherine Heigl Shares First Photo of Son Joshua

"I actually prefer the adoption way because I wasn't subject to hormones," she adds.

The Doubt actress says that the hormones are "the only difference" when it comes to her three children.

"The moment you hold your child, you're wholly in love," she explains. "And you'll do anything to protect them and shelter them."

Of course, Heigl says she's still glad that she experienced pregnancy, although it was unplanned.

"I've never been determined to experience pregnancy," she admits. "But I'm so grateful that I did. I think that if it hadn’t been a surprise, I'm not sure I would have done it. It was an incredible experience, it was kind of magical."

The mother of three shares she had an easy pregnancy -- minus the indigestion -- up until two weeks before her delivery date, when she found out that her son was breech, and had to schedule a cesarean section. Still, even that experience turned out to be better than she predicted.

"It was nerve-wracking, [but it] was all done in about an hour … It was way easier than I expected," she shares.

WATCH: Katherine Heigl's Daughters Help Dad Josh Kelley Write a Song on the Piano

On Wednesday, Heigl and Kelley shared the first photo of their son, posing for a sweet family photo.