The 31-year-old singer gave birth to her son Max Liron, which means 'greatest song', in January 2008 and rates having him with former husband Jordan Bratman above anything else she has ever done in her life, reported OK magazine.
"The birth of my son is my proudest moment. Max is my greatest song," Aguilera said.
'The Voice' mentor is taking time off from the show next year to focus on her music career and said that she will miss her fellow coaches - Cee Lo Green, Adam Levine and Blake Shelton - and the contestants.
"The coaches are like big brothers and the contestants are so hungry. I am better for it but I need to take a break to do my own thing, to bring so much back to them," she added.