Securing a copy of the baby's birth certificate, TMZ have claim that the document is proof that Stone gave birth to a baby girl, who she has named Louise Jean McCary.
And while the newborn dons a sweet, old-fashioned name, it’s actually more sentimental then many may realise. Stone’s middle name, Jean, came from her grandmother’s full name, Jean Louise, which Stone passed down in its entirety and flipped for her daughter.
Stone shares her newborn with husband and Saturday Night Live veteran, Dave McCary. After announcing their engagement at the end of 2019, the pair reportedly said “I do”, sometime near the end of 2020.
Despite her daughter being less than six months old, Stone proves that mothers can do both by heading straight back to work to promote her film, Cruella, at its premiere on May 18.
Back in January, a source close to the couple told E! that Stone is "very excited about her pregnancy and what's to come," adding that she is spending most of her pregnancy at her Malibu home, only travelling locally if she must.
The source also added that Stone has felt fortunate that she hasn't had to be on set while expecting. "She has always wanted a family and can't wait to be a mother," they said. "She's felt very lucky that she got to be at home during this period of time and wasn't working long days on set."
The source who spoke to E!'s also echos the information that another source told Us Weekly when news of Stone's pregnancy initially broke. "She seems very happy and very excited about becoming a mother—she's constantly oohing and cooing," the source said.
"She looks great, she looks healthy, she's glowing. She's been keeping up with friends and work lately, she's always staying active and gets her daily exercise in."
Stone has previously spoken about her dreams of becoming a mother while she's in her 30s, while speaking to ELLE U.S. in 2018.
"My perspective about kids has changed as I've gotten older," she told fellow actor and friend, Jennifer Lawrence. "I never babysat or anything. As a teenager, I was like, I'm never getting married, I'm never having kids. And then I got older and I was like, I really want to get married, I really want to have kids."
Congratulations to the new parents!