Williams, 40, is currently heavily pregnant with her fourth child with former Made in Chelsea star Spencer Matthews. With the help of an artfully placed water balloon, the presenter successfully pranked her Heart Breakfast co-host into thinking her water had broken. While complaining about her back pain, Williams discreetly popped the water balloon underneath her chair in the studio and looked over at Theakston in shock. she shouted, as Theakston rushed over to see what had happened, quickly pivoting to crisis management and taking Williams’ headphones off her. Theakston continued to ask if Williams could walk, suggesting they could call a taxi to the back of the building.