Molly Sims Shares Birth Story Following Son's Arrival, Explains Naming Him Grey Douglas

The 43-year-old model opened up about her growing family on Thursday.

Molly Sims is opening up about giving birth to her third child, and the inspiration behind his name.

It turns out that the 43-year-old model, who welcomed son Grey Douglas on Jan.10, went into labor a day before she was scheduled to have a Caesarean section.

RELATED: Molly Sims and Scott Stuber Welcome Baby No. 3, Share Adorable First Photo

"I'd never really gone through labor because both my babies were C-sections because of complications with my pregnancies," the mother of three reveals in a video posted to her YouTube page on Thursday. "I thought for sure this is going to be a C-section."

After securing a babysitter for their older children, 4-year-old Brooks and 1-year-old Scarlett, Sims and husband Scott Stuber rushed to Cedars-Sinai Medical Center in Los Angeles.

"I can't tell you how stressed I was," she confesses. "I was trying to make my husband go through red lights on Sunset [Boulevard] because we live quite far from Cedars. We got into an argument because he wouldn't run a red light, because I was having contractions."

Once they arrived at the hospital, Sims attempted to convince the doctors that she wasn't actually in labor, and could "hold off" until the next day.

"Nevertheless, I was in full-on labor," she recalls while cradling the newborn, and thanking the team of nurses for their hard work.

"It's crazy to watch those nurses and what they do, and how quickly they get in," she says before gushing over her son. "He's been fantastic."

WATCH: Molly Sims Reveals She Already Has Some Names Picked Out for Baby No. 3

Since the baby came ahead of schedule, Sims' parents missed his birth, and were introduced to their new grandchild via FaceTime.

"My mom burst into tears, it was a really special moment," Sims adds. "She always felt I was going to go [into labor] before she got here."

In regard to the baby's name, Sims admits to having a few different options in mind, but it was her son, Brooks, who spearheaded the naming process.

"Brooks had a lot to do with the name," she shares. "I know that sounds weird, but he would not give up on 'Grey.' It was 'Grey Jack and the Beanstalk Batman' all the way."

The baby's name was even more fitting because he was born on a cloudy day.

"Living in California, you're always used to sunny skies, and clear, but it was raining and very grey outside, so it was kind of suitable in a weird sort of way," Sims notes.

Towards the end of the video, Sims shows off a push present from her husband, which included a card and necklace reading, “M+S = B&S&G,” in honor of their family of four.

"I have to say, probably the card meant more than anything, but the necklace is just reminder of what I have and how special those four people are to me," she gushes.

WATCH: Molly Sims Opens Up About Her Most Difficult Pregnancy and Which Star Took Her Favorite Baby Name

Sims has been chronicling several precious moments since welcoming Grey into the family. She recently took to social media with snaps of her older children holding their new baby brother.

See more on Sims' adorable family below.