Carrie Underwood thinks her 3-year-old son, Isaiah, may have figured out that she was expecting a baby before she and husband Mike Fisher had the chance to break it down to him.

Talking to CMT's Cody Alan, Underwood recalls hanging with friends in her swimsuit on a lake recently. She was starting to show, and Isaiah "was just sitting there looking at my belly, and he starts squishing it with his hands," the "Cry Pretty" singer says. "I kind of thought he was gonna go in to kiss it and I was like 'This is about to be the sweetest moment. Somehow he knows."

"And then he literally goes in and like blows on my belly, like pfffft ... And I'm like 'OK, and you're three," Underwood says, "All of the sudden you're back to being three.'"

Underwood revealed that she and her husband of eight years were expecting on Aug. 8. They have not shared if they're having a boy or girl this time. In fact, she insists they don't know yet. When asked if she might wait until the CMA Awards to reveal the big news again (like she did in 2014), the 35-year-old admits she probably won't be able to hold a secret that long.

They're still trying to explain it to their toddler.

"He was a little confused, not really knowing how that got there," Underwood tells Alan about the magic of babymaking and how they explained it to Isaiah. "I just told him 'God put it there,' and we accepted that answer [laughs]. He’s just gonna be a good big brother. He’s a good little guy."

Underwood is feeling good about how her son will do as a big brother. She'll be counting on him when she begins the Cry Pretty 360 Tour next May. The family will travel together, meaning he'll be in very close quarters with baby brother or sister for long stretches.

Before revealing she was pregnant, Underwood talked to Taste of Country about her new Cry Pretty album, detailing some of the drama and collaborations. We admittedly missed some obvious clues that she had a baby in her belly.

Carrie Underwood Talks About her Cry Pretty Album

Relive Carrie Underwood's Best Pregnancy Pics!