'Grey's Anatomy' Star Caterina Scorsone and Husband Rob Giles Welcome Baby Girl Named Arwen

Caterina Scorsone‘s household just got another dose of sugar and spice!

The Grey’s Anatomy actress, 38, and husband Rob Giles shared the first pictures of their newborn daughter, Arwen Giles, in an Instagram post on Tuesday.

“Arwen is here!” Scorsone wrote in the caption of the picture that quickly garnered tens of thousands of likes within minutes.

The adorable pictures show big sisters Paloma “Pippa” Michaela, 3, and Eliza, 7, each with baby Arwen. The first picture, taken by photographer Rebecca Coursey, shows Eliza snuggling up to with Arwen on a colorful blanket, while the second shows Pippa gently holding her new sister in her arms.

“Our family wishes you a happy new year, a happy new decade and a happy heart made new by love in every exquisite moment,” Scorsone continued in the post.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Scorsone — whose Grey’s character Amelia Frances Shepherd discovered she was pregnant early this season — made her exciting pregnancy announcement alongside a photo of herself, her husband and their two older daughters dressed up as the Addams Family for Halloween.

In the shot, Scorsone, who wore a Morticia Addams costume, stood to the side and cradled her growing baby bump as her family posed beside her.

“Our Family’s about to get even kookier. #pumpkinintheoven ?,” she captioned the image, referencing a lyric from the show’s theme song.

The actress has been outspoken about raising her girls and how her perception of parenthood has shifted over time, especially after she learned that Pippa had been diagnosed with Down syndrome.

“What I unconsciously thought about my job as a mother was that I was supposed to equip her to survive in a competitive world,” Scorsone said in March on the Motherly podcast, explaining that she was initially sent “into a tailspin” when she realized Pippa “was going to have some physical differences and some cognitive differences.”

But one day, things just clicked. “This simple voice came to me where I was like, ‘I don’t know what to do — oh, I’m supposed to keep her safe and I’m supposed to make her feel loved,’ ” she said. “And suddenly my understanding of my job as a mother completely distilled and opened.”

Speaking with PEOPLE in April, Scorsone said of parenthood, “I think one thing that changes when you have kids is that nothing is in your control anymore. You have to roll with whatever is happening and there are people that are now in your life very intimately and in your space who have distinctly different personalities from you.”