Sarah Ferguson takes a pledge as Princess Beatrice prepares for childbirth

Sarah Ferguson he reportedly working on a new cause before Princess Beatrice gives birth the second time.

The Duchess of York is working to eliminate plastic diapers under a new initiative called The Greater Good.

Writing about it in a special piece for Daily Mail, Fergie admits this cause is close to her heart.

"In a few months I’m going to become a grandmother for the fifth time. August, Ernest, Sienna and Wolfie will be joined by another beautiful boy or girl, as our family grows once more," Fergie writes in an op-ed.

"As all grandmothers know, from story-time, to tea-time, to nap-time, family life is a hands-on affair – not least when it comes to changing nappies," she continued. 

"Over the course of my life I’ve been no stranger to it! When my first grandchild was born, I rolled up my sleeves as though a 30-year hiatus had never happened. Seeing nappy after nappy thrown into the bin, I began to wonder: what are these nappies made of and where are they going? Researching it, I was stunned: they are full of plastic waste, each one damaging our environment," Fergie wrote.

"With a new grandchild about to enter the world, and my career as a nappy-changer about to re-start, I am incredibly optimistic about the future of our planet, and this is entirely thanks to projects like this which are helping to protect the oceans for our babies to grow up and enjoy plastic-free.”

Princess Beatrice, is expecting her second child with husband Edoardo Mapelli Mozzi,