Click on photos for gallery of Zara at the races.
Wearing a beige jumper that stretched over her burgeoning bump, Zara wrapped up in a faux fur lined winter cape.
The blossoming royal, who is due to give birth early next year, tenderly touched her stomach as she walked around the racecourse.
While keen horsewoman Zara has put competing on hold during her pregnancy, the Olympic silver medallist looked in high spirits as she enjoyed the action from the side.
Zara watched as her husband Mike Tindall's horse, Monbeg Dude, came fourth in the Murphy Group Handicap Steeple Chase, ridden by her former jockey boyfriend Richard Johnson.
The 32-year-old seemed to be enjoying herself and soaked up the buzzing atmosphere at the Cotswold-based Paddy Power Gold Cup Day.
Zara was previously criticised for continuing to ride in the early stages of her pregnancy, even competing in a charity polo match when she was three months gone.
At the time, the royal's spokesperson said she was following her doctor's orders and "would never put her pregnancy in jeopardy".
Zara has tried her hand at baking instead, revealing last month that she riding was too uncomfortable.
"I have been riding, but it's so uncomfortable," said Zara. "So, yes, I'm baking. I love cooking and will definitely cook for the baby."
The beautiful blonde added that after giving birth, she plans to return to the competitive sport.
Zara and Mike do not yet know the gender of their firstborn, and said they wanted it "to be a surprise".
"I hope we're going to make good parents," said Zara. "That's the plan."