Alongside a photo of her entire brood dressed up as the Addams Family, Caterina captioned: "Our Family’s about to get even kookier. #pumpkinintheoven 🎃"
Caterina, her husband Rob and their two children, 7-year-old Eliza and 2-year-old Paloma, all posed in the Halloween-inspired post.
The actress's Grey’s Anatomy co-stars were quick to offer their well wishes to the couple.
Camilla Luddington commented: “Omg this is GREAT!!!!!!!!”.
While Alex Blue Davis wrote: “This is amazing.”
Caterina recently revealed the "tailspin" she went into when her daughter Paloma, who she affectionately calls Pippa, was diagnosed with Down syndrome in 2016.
“My whole concept of what motherhood was had to shift,” she said in March during an episode of the “Motherly” podcast.
“When Pippa was born, and I realised that she had Down syndrome and she was going to have some physical differences and some cognitive differences … I didn’t know what her capacity would be. It really did send me into a tailspin.”
She added: “How do I mother this child? If my job is not to equip her to compete and dominate socially, or educationally, or physically or economically … what is a mother? What is my job?”
Since her daughter's diagnosis, Caterina has become an advocate for those diagnosed with Down syndrome as she promotes it as a difference, not a disability.
On July 28 she shared a detailed post about her thoughts and feelings, saying no one "suffers" from Down syndrome.