The Olympic champion – who announced her first pregnancy in January – looked healthy and happy as she posed for pictures in Battersea Park on Wednesday (21 May).
Jessica – who looked great in a pink and black tracksuit - was unveiling a giant statue of a female runner to officially launch the Vitality Run Series.
Her appearance came three days after she celebrated her first wedding anniversary to husband Andy Hill, who gifted her with gorgeous flowers on the day.
Tweeting a photo of her bouquet, she said: "Beautiful flowers from my gorgeous husband. Can't believe we've been married a year today! #veryhappylady."
Jessica and construction site manager Andy married at the Church of St Michael and All Angels in Hathersage, Derbyshire on 18 May 2013. They became engaged on Christmas Eve 2010 and have been together for around ten years.
In January this year, the happy couple announced they are expecting their first child together, meaning Jessica pulled out of the upcoming Commonwealth Games in Glasgow.
At the time, Jessica said: "My plans for 2014 have been completely turned upside down, but having had a couple of weeks to think about things from a career point of view, I am 100% set on returning to full time athletics once our baby is born and go for a second gold medal at the Rio Olympics in 2016 - that challenge really excites me."
"But in the short term I will make our baby a priority and enjoy the whole experience as much as possible. I am sorry I won't be in Glasgow for the Commonwealth Games, but know it will be an amazing occasion. I will be at home awaiting the arrival of a little Ennis-Hill."
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