Biographer Ian Halperin claims several sources have told him the celebrity, formerly known as Bruce Jenner, is having doubts about her decision to transition from a male to a female.
Writing in the Daily Mail he says this is because of her Christian faith and beliefs that same sex relationships are sinful.
Caitlyn Jenner, 66, is still attracted to females, as she was when she was Bruce, so it is reported she has concerns she will not be able to have a relationship.
Ms Jenner's been open about her devout Christian beliefs and often attends church and Bible study.
Despite her agent describing suggestions she will detransition as 'idiotic' the journalist is standing by the story.
He claims to have spoken to several sources that say Ms Jenner is having second thoughts about a final operation that will remove her male genitalia.
In March she said: "One of the things I really had to deal with is, I've always wondered, because I felt like God made me this way, why did he do this?
"I kind of had somewhat of a revelation and that turning point was saying to myself maybe this is the reason God put me on this earth - to, number one, be open with myself about truly who I am as a person.
"There is nothing better in life to not have any secrets and living your life authentically. Nothing better than that.
"And two, maybe you can make a difference now."