How Carrie Underwood Found Out Her Baby's Gender

— -- Carrie Underwood and her husband, Mike Fisher, both had a feeling they were having a baby boy -- but they didn't want to find out in the doctor's office during her sonogram.

In fact, they went to great lengths to keep themselves in the dark.

"[The doctor's office is] kind of a sterile place," Underwood explained to ABC News Radio. "We got to see all the pictures and everything. It was really cool to see that, but whenever she'd get near, near those parts we would look away."

Instead, Underwood, 31, and her hockey player husband, 34, asked the doctor to write down the baby's gender for them to look at when they were ready. They took the envelope containing the news of the baby's sex with them out to a nice restaurant.

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"[It was] just the two of us in a nicer setting, but we both knew," she said. "So, that was just confirming our suspicions. We didn't really speak of it before, 'cause we were both just like, 'Whatever. It's all good.' But we knew it was a boy."

Of course, Underwood's CMA Awards co-host Brad Paisley told the world she was having a boy during the show earlier this month. She said she'd planned to announce the baby's sex during the show all along, but she didn't let Paisley in on the secret until the very last minute.

"Brad's got loose lips. He's a blabber mouth!" Underwood said with a laugh. "So, I was like, 'I'm not gonna tell you until we're ready for the rest of the world to know, 'cause I know you'll tell people.'"

The singer has another big delivery -- the double-disc compilation "Greatest Hits: Decade #1" -- due out December 9. The lead single from that project, "Something in the Water," is already a big hit at country radio.