Surprise! Ellen Pompeo is a mother of two.

Hours after announcing the birth of her second daughter Sienna May Ivery, with husband Chris Ivery, the 44-year-old "Grey's Anatomy" actress opened up to Jimmy Kimmel on Thursday about trying to keep the surrogacy process a secret.

"She was born two months ago," Pompeo told Kimmel. "The mayor of New York City married us, and I kept that a secret for five days, too, I've done it before. The covert thing is kind of fun. This baby was born via surrogate, so I felt an obligation to keep the surrogate's privacy. That was of utmost importance to me."

"And then today you said the hell with her!" Kimmel joked.

The actress's daughter joins five-year-old sister Stella Luna Ivery. Pompeo shared exclusive details about her new daughter, including being present for the surrogate's insemination.

"I was present for the insemination. I held her hand," she said. "They take the sperm...Medically, Chris Ivery has to do what he has to do and provide, and then I had to provide something as well, you know? You have to retrieve the egg. And then they put it together in a dish, the lab technicians, and then they make the embryo. Then they insert the embryo into the woman who will carry the child."

Pompep praised her surrogate, saying, "This is an incredible thing to do with your life, to give the gift of carrying someone's child, so I am forever grateful and feel very blessed and grateful to her - she who will remain anonymous. I was there with her when they inseminated her and we held hands. I looked into the microscope and I saw the embryo, I saw the baby, and they put it in a thingy and they inseminated her. And then we held hands and we prayed, we talked to god, and if she was meant to be. He said he was going to try to help us out and now we have a gorgeous baby girl."