All these years later, Alderaanians still spoke of “the accident” in hushed tones. It was the moment the monarchy nearly ended without an heir, the day when a beloved princess – even more beloved than Leia herself, as Leia well knew – had nearly died. Her mother had fallen while completing her Challenge of the Body; the resulting injuries could’ve claimed her life. She’d been saved through quick action by the guards observing at a distance, but some of the damage had bee permanent. It was after the accident that Breha’s heart and lungs had been replaced by the pulmonodes that still glowed faintly in her chest. And it was due to the accident that her parents had elected to adopt a child rather than strain Breha’s body further.
….
Bail and Breha Organa had waited a long time for a child. They had told her that many times, often as she went to sleep, as part of the story about when her father came home from a mysterious mission to surprise her mother with the baby girl in his arms. – Leia, Princess of Alderaan