Behind the scene was the speculation of his uncle, FUJIWARA no Tokihira that while his daughter was already sent to court to marry Emperor Uda and became a nyogo (a court lady next to the Chugu or the second consort), a prince had not been born yet, then prince Yasuakira was born and Tokihira wanted him to become Crown Prince and control the administration through him.
これは、叔父藤原時平の思惑があり、時平の娘は既に宇多天皇に入内し女御となっていたがなかなか皇子を生まず、そんな時に生まれた保明親王を即位させることで政治の実権を握ろうとしていた。