Kim Jong-un reportedly fathered a baby girl in 2010 with an unknown woman, more than two years before his wife gave birth to the couple's first child, it has emerged.
Kim is believed to have married Ri Sol-ju in 2009 but she only began to emerge alongside the young North Korean leader in July 2012.
"Ri Sol-ju performed on stage in 2010 as a member of the Unhasu Orchestra, when Kim Jong-un became the father of his first child," the Chosun Ilbo newspaper quoted a diplomatic source in Beijing as saying.
"In North Korea, it is unthinkable for a pregnant first lady to perform on stage."
The paper also reported a surge in imports of high-end Swiss and German baby products ahead of the new arrival, but suggested there was uncertainty about whether it would be a boy or girl.
"North Korea's recent imports of luxury European baby products included goods for both baby boys and girls," it said.
There have been no reports from within North Korea about the birth of either of Kim's daughters, which analysts attribute to the ongoing three-year official period of mourning for Kim's father, Kim Jong-il, who died in December 2011.
Kim Jong-il also had a complicated personal life and is understood to have been officially married only once, but to have had at least three mistresses.
As well as Kim Jong-un, Kim fathered two other sons and two daughters.
Dennis Rodman, the former US basketball star who visited Pyongyang at Kim's invitation in February, said Ri talked at length about her "beautiful baby daughter."
Kim, however, is likely to want to father a son and heir in order to continue the world's only communist dynasty.