Brittany Kerr Aldean‘s second pregnancy was an extremely welcome non-surprise.

The couple welcomed son Memphis and the country megastar and Field & Stream brand ambassador is also dad to two daughters from a previous marriage: Kendyl and Keeley.

“After having our son, we knew we wanted to have two kids,” says Aldean. “I have my two older daughters already, so after Memphis was born we knew we wanted to have another one pretty quick — to go ahead and knock it out and have one that was a little closer in age to him.”

“I would much rather knock it out now while we’re used to having one in diapers and formula and all of that,” he adds. “I think it’s tougher when you get out of that and wait a couple years and then have to go redo it all. … We just wanted them to be close in age, and we figured we’re already in that mindset now, so why not?”

The “You Make It Easy” hitmaker reveals he and Kerr Aldean underwent in vitro fertilization once again for their second child.

“We did IVF with our son, so we had to do that again with this one,” he tells PEOPLE, adding of the 𝚋𝚊𝚋𝚢’s 𝓈ℯ𝓍 (which they are keeping a secret for now), “We knew what was going on.”

Although the parents-to-be went into this pregnancy similarly to Kerr Aldean’s first, there have been some big differences since finding out they were expecting again.

“With my son, Brittany didn’t have any sickness at all, but with [this] 𝚋𝚊𝚋𝚢 she’s been pretty sick for the last few weeks, so we’ll see,” says Aldean. “Maybe she’s starting to turn the corner a little bit, but it’s definitely been a different kind of feel for her this time.”