Tori Spelling has played the good girl on "Beverly Hills 90210? and is starring as mean girl in the new ABC Family original holiday movie "The Mistle-Tones," but it's her real-life role as mother to four children that could be her most challenging.

Spelling, 39, gave birth to her fourth child, son Finn Davey McDermott, last August after a life-threatening pregnancy that left her pleading with doctors to save her baby.

"I remember at one point, one of my doctors said…'Just get, let's, let's get to 28 weeks. Get, get that baby to 28 weeks,'" Spelling told ABC News' Cecilia Vega in an interview that aired on " Good Morning America" this morning.

The actress and reality TV star was hospitalized for two-and-a-half months during the pregnancy as a result of a condition called placenta previa, in which the placenta covers the opening of the cervix, she earlier revealed to Us magazine. The condition most likely resulted in part from the C-sections she had with her three other children - Liam Aaron, 5, Stella Doreen, 4, and Hattie Margaret, 14 months - all with her husband, actor Dean McDermott.

WATCH: Tori Spelling on Being a 'Normal Mom'

The hospitalization and bed rest - she was forced to lay still on her back - left her unable to spend time at home with her children, something she called the "hardest" part of the pregnancy scare.

"I missed the big moments," Spelling told Vega. "I missed Liam's preschool graduation; Stella's birthday party; Hattie's when she first started to crawl [and] her first word."

Today Finn is a healthy 3-month-old boy and the child Spelling says she will always have a special bond with.

"With Finn though, I definitely appreciate every second more with him," she said.

This Christmas, Spelling is also appreciative of her return to acting in "The Mistle-Tones," where she stars alongside Tia Mowry as rival singers, and spending time at home, again, with her family.

"We're such a DIY family that the holidays, it's like our perfect holiday," she said. "We make everything. We make our ornaments and anything we can make, we do."

Spelling famously grew up as the daughter of legendary television producer Aaron Spelling who was Jewish, along with her mother, Candy. That religious difference did not stop the Spellings from celebrating Christmas, including having a room in their famous mansion devoted to just holiday wrapping.

"We grew up celebrating everything," Spelling told Vega. "Because they [her parents] believed it wasn't about a religious holiday, it was about a family celebration."