"I was happy either way no matter what we were gonna have, but Nathan was especially excited because he's a boy, so he was like jumping for joy," the Teen Mom 2 star told Us Weekly. "He's really, really excited to spoil him."
Jenelle, 21, is currently almost five months along in her pregnancy, and she and Nathan reportedly decided to name their baby boy Kaiser.
"We were basically searching for baby names on the Internet, and we came up with a bunch of different unique ones," she revealed. "We didn't want something that everyone else had or had even heard before, even us. So we wanted something different, and we ended up looking up Kaiser."
Reports Jenelle's expecting her second child first surfaced in December. She already has a four-year-old son named Jace from a previous relationship.
"[Jace has] been talking about how he can teach him little boy things now," Jenelle told the magazine.
"He said he can teach him how to play football, he said, 'I can teach him how to put on his clothes,' because we were talking about how he's gonna get Jace's old clothes when he grows out of them. So he's really excited to help out."
Jenelle has apparently had a tough pregnancy so far, experiencing weeks of morning sickness and exhaustion on top of trying to handle her academic load as a college student.
"Recently I've been tired," she said. "I have to power through the days, because I go to school now on Tuesdays and Thursdays for medical clinical assisting."
Jenelle's mother Barbara Evans still has full custody of Jace, however, a newly-sober Jenelle is reportedly looking to turn over a new leaf and start over with her second son. She's been arrested 10 times over the last three years from alleged drug and relationship issues, according to Us.
Nathan also reportedly has a two-year-old daughter, Emery, whom he does not have custody of. Jenelle and Nathan allegedly moved in with one another in June of last year.