In an emotional statement the 27-year-old heptathlon champion expressed the couple's excitement at the "unexpected" news, which has turned her plans for 2014 "upside down."
Jessica had been planning to compete in the 2014 Commonwealth Games in Glasgow, but will instead be spending July awaiting the imminent arrival of baby Ennis-Hill.
The sports star said in a statement: "I have some very unexpected but exciting news to share – Andy and I are expecting a baby. We are completely overwhelmed, with excitement and a degree of anxiety that I am sure all first time parents will relate to.
"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 100Slideshow-84534%