Pippa Middleton has been sighted out in public displaying her blossoming baby bumpMORE: Pippa Middleton rocks mom jeans and designer trainers in new picturesIn pictures obtained and published by the Daily Mail, the pregnant 37-year-old could be seen smiling and walking around London with her son.The Duchess of Cambridge’s sister wrapped up her baby bump in a stylish grey overcoat alongside some biker boots and chic sunglasses.A decade of style with Pippa MiddletonPippa is already the doting