In each of zeroglotte's languages, there is a word for somebody who loses her parents: orphan, orpheline, orfã, Waise. And there is for one what you become if you lose your spouse: widower, veuf, viuvo, Witwer.
But if your child dies, there is no word for that.
Of course you have only one set of parents, and, at least traditionally, only one spouse, while you used to have a whole bunch of children and it was expected that not all of them would grow into adults.
With so many neologisms of all kinds, nobody wants to invent that word. Keep harm out of the way. Nobody needs it.