Sarah Jessica Parker sat down with Access Hollywood's Billy Bush earlier this week on the New Mexico set of her new comedy, "Did You Hear About The Morgans?" for her first interview since announcing that she and husband Matthew Broderick are expecting twins through a surrogate.

"I'm excited," she told Billy about the babies. "I'm in disbelief. I'm really grateful. I feel really fortunate. My son is so excited, my husband is so excited."

On April 28, just as stories were about to break with the news, the couple announced they were expecting twins via a surrogate. And on Tuesday, Sarah Jessica told Billy why she chose to go the surrogate route.

"Well, you know, we've been trying to expand our family for a number of years and we actually have explored a variety of ways of doing so," she said. "This was one of the things we discussed with seriousness that had real possibilities for us."

"A lot of people face disappointment in that area – [did you have your] fair share of disappointment?" Billy asked.

"Yeah, I mean I couldn't pretend otherwise," she said. "It would be a complicated – it would be odd to have made this choice if I was able to, you know, have successful pregnancies since my son's birth."

Thrilled over the fact that she was indeed having a child via surrogate, when Sarah Jessica learned she was having twins, her glee doubled.

"I mean, giggles!" she said of her reaction when first learning the news. "We didn't expect it. I think after a certain amount of time, you tend to hold your hopes at bay a bit so as not to be disappointed. One really would have been thrilling and we would've felt incredibly lucky. And two was a comedy!"

Sarah Jessica said she has shared with her son, 6-year-old James Wilkie, some details about the surrogacy, but at first refrained from telling him too much.

"I've been pretty candid with him," she said. "I kind of chartered my own course with him because we wanted to keep this quiet and so I wanted to be very careful about telling him so he wasn't burdened with a secret. On the other hand, I wanted him to have time to adjust to the idea of sharing his mama and his papa."

And now that he has, Sarah Jessica said James is ready to be a big brother.

"I feel very excited about the fact that my son is of an age now where he really will be helpful," she said. "He's really excited. He's very much ready to be an older brother. I think it gives him a great sense of pride. It's wonderful and I just hope for their safe arrival."

Safety is, in fact, Sarah Jessica's main concern. Since the baby news broke, she's been shocked that a tabloid has targeted her surrogate.

"What has happened to her?" Billy asked.

"What hasn't happened?" Sarah Jessica replied.

Not only has the woman carrying the twins been identified, but she has been followed, something that is troubling for the star.

"I am incredibly outraged by the sort of extraordinary and unprecedented invasion of her privacy," Sarah Jessica said.