Teen Mom 2 #TBT: Remembering Jace's First Big-Brother Moment

See how Jenelle's firstborn reacted when told that Kaiser was on his way

Jenelle lovingly told her two boys Jace and Kaiser that they would soon have a little sister during this week's Teen Mom 2 episode (relive the reveal below). But this milestone occasion -- disclosing to a child that they are about to have a sibling -- is not unfamiliar territory for the North Carolina mama on the MTV program.

Jace -- who made his big debut during the second 16 and Pregnant season -- found out that he was going to be a big brother in the docu-series' fifth installment.

"I want to show you something," Jenelle sweetly explains in the old-school clip below as she holds a sonogram. "This is a picture of a baby in mommy's tummy."

How does her firstborn react to this life-changing news? Watch the mother-son's interaction in the video above, and don't miss Jenelle and her clan as they get ready for Baby Ensley, every Monday on Teen Mom 2 at 9/8c!