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Gwen Stefani’s ‘firstborn baby boy’ is 16 — see her throwback tribute

The singer shared an adorable flashback photo and a gratitude-filled message for her son Kingston.

Happy birthday to Kingston Rossdale!

The son of pop star Gwen Stefani and her ex-husband, Bush rocker Gavin Rossdale, turned 16 Thursday, and in honor of his big day, Mom celebrated her beloved “baby boy” on Instagram.

“I can’t believe that I’m actually writing this but.... a very happy 16th birthday to my firstborn baby boy @kingsrossdale_,” the “Hollaback Girl” singer wrote alongside a throwback pic. “I prayed and I waited my whole life to be a mommy — i’m so blessed that God chose me to be yours.”

The photo the 52-year-old shared alongside that sweet message showed her and a much younger Kingston smiling broadly as she held him in her arms.

"You r so loved and we can’t wait to see what happens next!!" she continued. "Got a feeling it’s gonna be good!! love u mom (gx)."

Related: Gwen Stefani poses with her 3 sons and Blake Shelton in sweet wedding-day pic

Kingston’s dad also wished him a sweet 16 on Instagram, calling the teen a "force of light."

“You have bloomed like an ancient spirit. i am thrilled for what is to come. i watch with great pride and excitement. with so much tragedy in the news it makes me even more grateful for you and the inspiration you bring to those who love you,” Rossdale wrote.

Rossdale also took the party to Instagram last year with a photo and moving message

"You are my best focus and inspiration — you are smart funny and kind with oceans of empathy — to me that’s all you need to make your mark," Rossdale wrote. "i could not be more proud of you — and i love you more every day — i am in awe of you — shine on."

And just one year before that, Kingston's now-stepfather, Blake Shelton, got in on the family celebration in an affectionate clip Stefani shared with her fans and followers.

Stefani and Rossdale, who were married from 2002 until 2016, share two other children together, sons Zuma, 13, and Apollo, 8.