The news was revealed on War Child USA's Instagram account, an organization that works to help children in war-affected communities reclaim their childhood through access to education, opportunity and justice. Seyfried and Sadoski are ambassadors of the organization and released a statement in a post, alongside an adorable picture of their newborn. Seyfried and Sadoski are also parents to their 3-year-old daughter, Nina, whom Seyfried gave birth to in March 2017.
Brie Bella and Daniel Bryan
The 36-year-old Total Bellas star gave birth to her second child, a baby boy named Buddy, with her husband on Aug. 1 -- a day after her twin sister, Nikki, had her first child. Little Buddy joins their 3-year-old daughter, Birdie.
Desi Perkins and Steven Perkins
The makeup expert announced on Oct. 20 that she had given birth to her and her husband's first child together; a baby boy. Over the years, Desi had been candid about her pregnancy journey, sharing that she suffered a miscarriage in 2013 before deciding to undergo in vitro fertilization.
Eniko and Kevin Hart
The couple had their second child together on Sept. 29. Eniko took to Instagram to announce that she had given birth to a baby girl, Kaori Mai Hart. Their daughter joined their 2-year-old son, Kenzo, and Kevin's two kids from his previous marriage to his ex-wife, Torrei -- 15-year-old Heaven and 12-year-old Hendrix.
Gigi Hadid and Zayn Malik
The supermodel and the singer welcomed their baby girl in September. The two shared the news on their social media on Sept. 26, with a sweet photo of their daughter's hand. They have yet to share her name.
Hilaria and Alec Baldwin
On Sept. 8, the proud parents added their fifth baby to the bunch, son Eduardo Pau Lucas. Hilaria and Alec's fifth child came after she had suffered a miscarriage at the end of last year. The pair also share 7-year-old Carmen, 5-year-old Rafael, 4-year-old Leonardo and 2-year-old Romeo. The actor is also dad to almost 25-year-old daughter Ireland, whom he shares with his ex-wife, Kim Basinger.
Jessica Biel and Justin Timberlake
Talk about surprise of the year. While the couple has yet to officially confirm that they added a second child into their lives, after months of speculation, Timberlake's former fellow *NSYNC group member, Lance Bass, confirmed to ET in September that the couple welcomed a second baby earlier this year. Timberlake and Biel are already parents to 5-year-old son Silas.
Jude Law and Phillipa Coan
The 47-year-old actor revealed that his ladylove gave birth to their first child together during his appearance on The Tonight Show Starring Jimmy Fallon on Sept. 15. This is Law's sixth child. He and his ex-wife, Sadie Frost, have three children together -- 23-year-old son Rafferty, 19-year-old daughter Iris and 18-year-old son Rudy. Law also has a 10-year-old daughter, Sophia, with model Samantha Burke, as well as a 5-year-old daughter, Ada, with singer Catherine Harding.
Katy Perry and Orlando Bloom
Daisy Dove Bloom came into this world in August. The Hollywood stars let UNICEF share their happy news on their social media on Aug. 26. The organization congratulated Bloom and Perry alongside a photo of the new parents holding their baby's tiny hand.
This is the first child for Perry and the second for Bloom. The actor shares a 9-year-old son, Flynn, with his ex-wife, Miranda Kerr.
Lea Michele and Zandy Reich
On Aug. 20, the former Glee star and her husband's lives changed forever. The couple welcomed a baby boy named Ever Leo, a year and five months after getting married.
The Supergirl actress gave birth to her and her husband's first child in September. They waited a couple of weeks to share their happy news and reveal that they had a baby boy, whom they named Huxley Robert Wood.
The Late Night star surprised many when she announced during her appearance on The Late Show With Stephen Colbert on Oct. 8 that she had become a mother of two. Kaling shared that she welcomed a baby boy named Spencer. She is also mother to daughter Katherine, whom she also secretly welcomed in 2017. Kaling has not revealed the identity of her children's father.
In late September, director Victor Kossakovsky revealed that Mara and Phoenix officially became parents. While addressing the audience at a Zurich Film Festival screening of Gunda, which Phoenix produced, the filmmaker announced that the actress had given birth to her and the actor's first child. Kossakovsky reported that the couple named their "beautiful son" River, after the actor's late brother.
On April 30, the singer revealed via Instagram that she's about to be a mom of three, expecting her second child with her husband. The two are already parents to 4-year-old daughter Jagger, while Simpson shares 11-year-old son Bronx with ex-husband Pete Wentz.
The Vanderpump Rulesstars confirmed to ET in September that they're expecting their first child together and that their little one is due in April 2021. A week later, the couple revealed on their social media that they have a baby boy on the way.
Emma Roberts and Garrett Hedlund
After months of speculation, the actress confirmed her mom-to-be status, showing off her baby bump on Aug. 31. In addition to confirming that she's expecting, Roberts adorably revealed that they will be having a baby boy.
Princess Eugenie and Jack Brooksbank
Another royal baby is on the way! Buckingham Palace announced on Sept. 25 that the princess is pregnant with her first child. The couple, who said "I do" in October 2018, will be welcoming their newest addition in "early 2021."
Kelly Rowland and Tim Weatherspoon
The 39-year-old singer debuted her baby bump on the cover of Women's Health on Oct. 7, and revealed in the accompanying interview that she and her husband are expecting their second child later this year. The couple, who tied the knot in 2014, already share a 5-year-old son, Titan.
Lala Kent and Randall Emmett
The Vanderpump Rules star and the producer have a baby on the way. The engaged couple shared the news on their podcast, Give Them Lala ... with Randall on Sept. 2. Emmett is already father to two daughters, 10-year-old London and 6-year-old Rylee, whom he shares with his ex-wife, You star Ambyr Childers.
Mandy Moore and Taylor Goldsmith
The This Is Us star is going to be a mom! On Sept. 24, the actress and singer shared the exciting news that she and her husband are going to be parents for the first time. Moore and Goldsmith will be having a baby boy in the coming months.
Meghan Trainor and Daryl Sabara
Congratulations are in order for this twosome! The "All About That Bass" singer announced she's pregnant with her and her hubby's first child together during her surprise appearance on the Today show on Oct. 7. She later Instagrammed the news, sharing they're "excited to meet this little cutie early next year!"
The Mean Girls actress is pregnant with her second child. McAdams was photographed leaving a children's store in Los Angeles in August, with her baby bump on display. McAdams has always been notoriously private about her personal life. She gave birth to her son in April 2018 -- whom she shares with her boyfriend, screenwriter Jamie Linden -- though she has never revealed his name.
The married twosome are going to be parents! The Duck Dynasty star and her husband took to Instagram on Oct. 4 to reveal that they are pregnant with their first baby. Robertson excitedly shared the news with fans alongside a sweet snapshot of her and Huff hugging on a couch and holding up a series of ultrasounds.
Sasha Pieterse and Hudson Sheaffer
The Pretty Little Liars star is pregnant with her first child. The actress, who is best known for playing Alison DiLaurentis on the Freeform show, announced on May 27 that she and her husband are expecting their first child together. She shared the news on her wedding anniversary.
Usher and Jenn Goicoechea
On Sept. 4, the 42-year-old singer revealed on Good Morning America that he is expecting a child with his girlfriend. This marks Usher's third child, and his first with Goicoechea. Usher is already a dad to his two sons with his ex-wife, Tameka Foster -- 12-year-old Usher V and 11-year-old Naviyd.
Witney Carson and Carson McAllister
The DWTS pro took to Instagram on July 23 to share that she is pregnant with her and her husband's first child together. Carson is due in January 2021. The pair are high school sweethearts who wed in January 2015.
See who else has a baby on the way in the gallery below: