United Kingdom, Oct. 2 -- Jesse McCartney and Katie Peterson are expecting their second child.

Taking to Instagram on Thursday (01.10.26), they revealed they are set to give their 17-month-old son Archer a sibling in March.

They shared a series of cute family shots, including one of the tot touching Katie's blossoming bump, and another of the couple proudly showing off their baby scan, alongside the caption: "Archer is getting promoted to big brother. March 2027."

Fans flooded the post's comments section with congratulatory messages, as one penned: "Ahhhh! I'm so happy for you guys. I hope you have a smooth pregnancy, labor, and delivery! This is amazing. (sic)"

A second supporter typed: "These babies are so lucky to have you guys as ...