Mae Whitman has officially entered parenthood.

The Coxno ExchangeParenthood star announced the birth of her first child—a son—on Aug. 28, sharing a photo of the newborn's feet while referencing Justin Bieber and Hailey Bieber's recent baby news.

"Not to be a Bieber about it but I too just gave birth to our son, Miles," Mae wrote on Instagram. "From the moment we heard the first tiny sound out of his tiny piggy mouth we were besotted."

Calling him "the kindest, gentlest, smartest, funniest little beebee," the 36-year-old went on to reveal that her baby boy was named after Parenthood costar Miles Heizer, who played her younger brother on the NBC show.

"He’s our best friend (pretty much exactly like his namesake Uncle Miles)," Mae continued of her child, who she welcomed with an unnamed partner. "We are infinitely grateful he chose us as his parents."

She added, "We love you! We’re so happy!"

Indeed, Mae and Miles, 30, have kept in touch since their show ended its six-season run in 2015. In fact, he was there—alongside with their onscreen mom Lauren Graham—when the Good Girls actress announced her pregnancy.

"Not to make a parenthood episode out of it or anything but," Mae wrote on May 12, sharing a photo of herself baring her baby bump next to her former castmates, "Mother's Day looking a little different this year!"

She continued at the time, "Can't wait to meet you, huge baby kicking my insides to filth!"

Likewise, Mae is still very close to Lauren and considers the Gilmore Girls alum to be one of her "best friends."

"I wish words could convey the depth of my love and gratitude for you," she wrote in a 2023 tribute to Lauren, "but they can’t so I’ll do us both a favor and not try."

Mae added, "Weeeee I love you LG."

She has not spoken out on her relationship status or identity of the baby’s father.

For the latest breaking news updates, click here to download the E! News App