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Giuliana and Bill Rancic's hope to have another child, in addition to their 2-year-old son, Duke, has taken a big blow.

The "E! News" host, who has been under a firestorm of controversy about her weight, said she learned on New Year's Eve that the surrogate who was carrying her third and final embryo had miscarried.

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The couple's struggled with fertility has been well-documented on their reality show, "Giuliana and Bill," as well as in the media. Because of Giuliana's cancer-suppressing medication following her 2011 breast cancer diagnosis, it would be incredibly risky for her to get pregnant. The couple's hope was for the embryos to work.

"It was painful," Giuliana told PEOPLE. "We were so optimistic with this last embryo. We thought, 'This is definitely going to work. This is our last shot.'"

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According to PEOPLE, after Duke was born, the couple had three remaining embryos and hoped to give Duke a sibling. Two of the embryos were successfully implanted in their surrogate in 2014, but she miscarried a few weeks later. The latest loss, however, "was the toughest blow," Giuliana says. "It was a really hard time."

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Although the latest news is a huge setback for the Rancic's, they are not giving up on the idea of adding to their family.

"We're open to everything," Giuliana said. "I think adoption is a beautiful gift you're giving each other. And it's funny, I'm even more open to [adoption] than I was before. Because I think to myself, 'I love Duke so much, if I couldn't take care of him, I hope there would be someone else who would love him.'"