Surprise! Ellen Pompeo is now a mother of two girls!

The 44-year-old actress, best known for her role as Meredith Grey in the long-running ABC medical drama series "Grey's Anatomy," revealed Thursday, Oct. 2, that she and husband Chris Ivery welcomed their second child together about two months ago.

"Sienna May Ivery welcome to the world. We love you more than words can say," Pompeo wrote on WhoSay and Instagram Thursday along with a photo of her 46-year-old music producer husband holding their precious newborn.

The Golden Globe-winning actress also took to Twitter and wrote: "Sienna was born via surrogate & I would like to thank my whole @ShondalandTV family for helping us enjoy these first few weeks privately ❤U."

When asked by Australia's TV Week how she managed to keep their new bundle of joy a secret for two months, Pompeo said that she is good in keeping private details under wraps.

 "It's important to protect the privacy of the surrogate," she explained, "but don't forget, I am the same girl who had the Mayor of New York City marry me and it didn't get out for five days so I'm good at that!"

Pompeo and Ivery, who also quietly tied the knot in New York City in November 2007, welcomed their first daughter Stella Luna in September 2009, Us Weekly reported.

The "Catch Me If You Can" star revealed that sometimes her 5-year-old daughter feels jealous of her little sister.

"The one thing that is amazing about Stella is I have really raised her to express what she feels and what she is thinking at all times so if she is feeling jealous of her sister, she says it and I understand that and say, 'Let's have some alone time.' I'm very proud of the way she's handling it," Pompeo told TV Week.

During an appearance on "The Ellen DeGeneres Show" in April, Pompeo talked about her intelligent-sounding eldest daughter.

"Well, today she told me I ruined her life," Pompeo said, laughing, as quoted by E! News. "She's 4 1/2. So yesterday, she said to me, 'Mama, this is the best Easter I've ever had and you're the best mom in the whole world,' and I said, 'thank you, Stell.' And this morning she woke up and said, 'I don't want to take swim lessons, it's my life and my choice, and you're ruining my life.'"