She signalled the start of the Beyond The Treatment fundraiser with a blast of an air horn in front of media cameras at Sheffield’s Weston Park Hospital.
The money will refurbish and modernise wards, introducing home comforts and including the introducing of WiFi and tech solutions so patients can video chat to relatives.
VIDEO: Watch the official Beyond The Treatment video - CLICK HERE.
MAKE A DONATION: To donate to the Beyond The Treatment appeal or to find out more visit www.beyondthetreatment.org.uk
Jess, a patron of the Weston Park Cancer Charity since 2011, put on a hard hat to tour wards where extensive building work is already underway and said: "We need to raise £500k to give two wards a big refurb.
"I live in the city. I've had friends and family who have visited this hospital. It's great to have this hospital here. To be able to be in a position to draw people to the appeal and give money, to make the hospital better for our city, is a very privileged position to be in."
Looking radiant the mum-to-be, who recently released her first children's book, Evie's Magic Bracelet: The Silver Unicorn, added: "I've a very exciting year ahead. I'm feeling very well. I'm due in the autumn, so a while to go yet but I'm jeeping busy.
"My first book is out and it's going to be one of seven, so lots more books coming out and it's been really great fun to do."
The appeal will also buy recliner chairs, circadian lighting to help patients sleep and an activity hub with access to iPads, DVD players, books and magazines.
A service to provide headscarves and support for people who have lost their hair as a result of their treatment, will also be paid for through the project.
Weston Park Cancer Charity needs to raise £500,000 by the end of September to cover the costs of the refurbishments and is calling on South Yorkshire businesses, community groups and individuals to help.
Weston Park Hospital admits 3,500 people every year, from Sheffield, Rotherham, Barnsley, Doncaster, Worksop and Chesterfield. The refurbishments will make sure they are more comfortable whilst they undergo their cancer treatment.
Samantha Kennedy, director of Weston Park Cancer Charity, said: “Going through treatment for cancer can be exhausting, painful, and often quite lonely, so we’re determined to help patients and their loved ones feel at home during their time in hospital."
Former patient Andy Gardiner, aged 66, of Nether Edge, is backing the appeal, in recognition of the care he received at the hospital five years ago.
He said: “The care I received was outstanding, but a television, internet connection, a reclining chair, a private toilet - things we take for granted at home - would have helped enormously. I urge everyone to get behind this appeal."