The 35-year-old Lost alum told E! Online that she's 7 months along, is due in September and has been having a "pretty straightforward" pregnancy so far.
"This is my second time around, and I find I've been pretty lucky," she told E! News. "It's pretty straightforward, and I just love it. I feel good, I feel blissful."
Lilly has a 4-year-old son named Kahekili with her longtime boyfriend Norman Kali.
And odds are this won't be her last pregnancy, as she elaborated on in an interview with Ocean Drive last year.
"What I wanted originally was six kids. I frickin' love being pregnant. I'm one of the lucky women who just had a blissful pregnancy, but I wanted to adopt four. My partner and I have really been through the ringer in the adoption world and it's hard, so we'll see what happens. Life is magically beautiful, and it brings you what is perfect."