The 31-year-old singer has admitted claims she is expecting her first child with NFL star Eric Johnson are true via twitter.
Uploading a picture of her dressed up as an Egyptian mummy and cradling her baby bump, Jessica added: "It`s true - I`m going to be a mummy!"
Jessica - who is engaged to marry Eric - has been keeping quiet about her pregnancy for some time, despite pictures revealing her to be expecting.
It has been claimed the country singer is expecting a girl after finding out the sex during a routine scan.
A source said: "She`s telling people it`s like winning the lottery, twice. Jessica really wanted to find out the baby`s sex, she hates surprises. She and Eric are both so happy."
Jessica`s mother Tina recently revealed she was keen to extend her family and give her two-year-old grandson Bronx - the offspring of daughter Ashlee Simpson and estranged husband Peter Wentz - a cousin.
She said: "Obviously I`m looking forward to having more grandkids. Bronx is the love of my life. I don`t mind boys or girls, I`ll take anything I get. I`m not picky!"