Carrie Underwood released her 25th music video back in September and on Friday the pregnant country superstar opened up about the process for creating her hit single Something In The Water.

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"Whenever you go into a writing session, for me, I really like not having too much of an agenda," the 31-year-old told People on Friday. "I always keep a little notebook of ideas that I'll draw from, or not. It kind of depends on what the vibe is for the day."

In writing the first of two original songs on her upcoming album, Greatest Hits: Decade #1, Underwood worked with Chris DeStefano and Brett James.

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"Chris had this music track that he'd been working on at home," Underwood noted, "And he came in and he's like 'It's either awesome or horrible and you're going to take it.' I mean Brett and I were both completely into it. It just sounds so like energetic and happy. I started flipping through my pages and was like I have this title called, Something In The Water. And that was that."

While the country singer has spent 10 years in this business, the music video for Something In The Water would be a new experience. In September Underwood announced that she and her NHL husband Mike Fisher are expecting their first child together, meaning the video would be the first to feature her budding baby bump.

In addition to impacting costumes, pregnancy likely influenced Underwood's movement for the music video.

"[Director] Raj Kapoor has always been really great with dancers and writers and movement and things like that…" explained the singer. "I think we really just wanted [the video] to match the energy [of the song] and have something really beautiful."

"I think it's really special," the mother-to-be admitted of her latest single. "And the I think it's the perfect way to mark ten years, being as blessed as I have been and as lucky has I have been being able to do what I do."

Greatest Hits: Decade #1 hits stores Dec. 9.

Underwood is due to give birth to her son sometime in the spring, though she and Fisher are keeping the exact date a secret for the time being.

Tags: Carrie Underwood Mike Fisher Music