Culture March 1, 2019

Meryl Streep is a grandma! Daughter Mamie Gummer welcomes baby boy

Christopher Polk/Getty Images
Mamie Gummer (L) and Meryl Streep attend an event on Feb. 21, 2017, in Beverly Hills, Calif.

Meryl Streep may have 20+ Oscar nominations, but she's stepping into a role she's never done before -- as a first-time grandmother.

Her daughter and "True Detective" star Mamie Gummer welcomed a baby boy earlier this week, according to US Weekly, who confirmed with the actress' rep.

(MORE: Oscars 2019: A look back at some inspiring, memorable speeches from Meryl Streep, Halle Berry and more)

Not much more is known, just that reports of Gummer expecting with Mehar Sethi began late last year.

Gummer is also not too active on social media, so don't expect any updates there. A request for comment or confirmation from Gummer's rep was not immediately returned to ABC News.

Sthanlee B. Mirador/Sipa USA via AP
Mamie Gummer arrives at the HBO's "True Detective" Season 3 Los Angeles Premiere held in Los Angeles, Jan. 10, 2019.

Mamie, 35, is one of four children of Streep, 69, and her husband Don Gummer. The duo are also parents to Henry, Grace and Louisa.

US Weekly adds that Gummer and her fiancé Sethi, who is a producer, got engaged last August.

(MORE: First look at Meryl Streep and ‘Big Little Lies’ cast in highly anticipated 2nd season)

Both the iconic mother and daughter are busy making waves at HBO, with Gummer just finishing a run on "True Detective" opposite Oscar-winner Mahershala Ali.

Streep, meanwhile, is a highly-anticipated addition to the second season of "Big Little Lies."

Show star Nicole Kidman shared a shot recently featuring Streep, who is joining the cast as the mother of Kidman's character's husband, played by Alexander Skarsgard. Not much else is know about that big second season.