The plea in appeal of the accused to obtain a provisional release pending trial was rejected after the judge said that there was a real danger that Mugabe would flee justice.
In addition, the prosecutor said the accused, in 2018, defiled the minor by luring her to sit on his laps.
The Rwandan journalist is suspected of impregnating the 19 year-old and attempting to persuade her to abort the pregnancy.
According to charging documents, law enforcement officers met with the victim's mother who reported that her two daughters were in a sexual relationship with Mugabe, and that it had been going on for the past several months.
If convicted, the Rwandan Managing Editor risks a 5-year jail sentence minimum, judicial reports said.