The books and two film adaptations, starring Renee Zellweger as the titular heroine, were based on a newspaper column Fielding began writing in 1995.
"I'm having a lot of fun and it's very funny and it's making me laugh," Fielding told the BBC about returning to Bridget's story.
"After the unexpected success when it first came out, I was startled by the whole thing," she said.
"When I first wrote it, I didn't think anyone would read it. It was just a column in The Independent, so it was very easy to write and be very honest -- and then I got all self-conscious because I knew so many people would read it."
Fielding said she was inspired to revisit her famous character in the spring of 2011.
"I had new stuff I wanted to say and things that were making me laugh," Fielding told the BBC. "Things that didn't exist when I wrote the last 'Bridget,' like emails really, and texting, the way life is lived through texting and Twitter, and a whole new idea for a phase of her life. It's more like, 'Number of Twitter followers: 0. Still no followers. Still no followers'. But she has grown up. My life has moved on and hers will move on, too. She's still trying to give up [drinking and smoking], she's still on a diet. She's trying a bit harder, and is a bit more successful, but she's never really going to change."
"Bridget Jones's Baby," a film based on the last of Fielding's newspaper columns, is in the works with Zellweger to return as Bridget, and Colin Firth and Hugh Grant to reprise their roles as her suitors Mark Darcy and Daniel Cleaver, the BBC said.