'Big Bang Theory' star Johnny Galecki, 44, welcomes first child with 22-year-old girlfriend Alaina Meyer

Johnny Galecki is officially a father!

The 44-year-old former "Big Bang Theory" star announced on Instagram on Wednesday that his girlfriend, Alaina Meyer, 22, had welcomed their first child together -- a son named Avery.

"With full and grateful hearts we welcome our beautiful Avery into this incredible world," he captioned a black-and-white photo the new parents' hands grasping their newborn son's. "Thank you for all of your love and support."

The couple announced that they were expecting a child together back in May, the same month that they held a gender reveal party announcing that they were welcoming a son.

"We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world," they shared at the time. "There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours."

Galecki and Meyer, who have raised a few eyebrows with their 22-year age difference, first went public with their romance back in September 2018, at the start of the final season of "The Big Bang Theory," which came to an end this past spring.