The 31-year-old singer spoke to the Today show in the U.S, admitting she was already 'looking forward to the second trimester' when the sickness is meant to subside.
Blonde Kelly, who made her name on talent competition American Idol, married Brandon Blackstock last month - and said she has been 'dying to tell people' about her pregnancy.
However, like Kate Middleton's case, where she had to admit the pregnancy earlier due to suffering from such bad morning sickness, Kelly found she had to do the same.
In fact, she experience sickness so bad that she had to cancel a show.
'I didn't want people to think I was cancelling [beacause] I was lazy or something, so we just told people. But we had a really good reason.'
And the star claims she knows she's expecting a girl, saying: 'Of course it's a girl, causing the trouble.'
Husband Brandon, who is an artist manager, has two children from a previous marriage.