According to sources, Jenner told producers two weeks ago that he had concerns about the show's psychological effect on his children. Jenner wants to make sure his three sons, including The Hills star Brody Jenner, are "in a good place" to handle his transition.
In addition to his concerns about his family, Jenner also wanted to take time to deal with the emotional repercussions of causing a recent car crash which left one woman dead.
"There's a 99.9% chance the docuseries will happen," a source said, but the show will no longer happen in May. However, Jenner's interview with Diane Sawyer is still scheduled as planned.