In the episode Elogium in Star Trek: Voyager, Kes, an Ocampa, enters into what we later find out is a false elogium, which is essentially like entering puberty. This happens once in a lifetime for Ocampa and if they are to mate, it must be within a limited time period after the elogium.
It's clearly stated the elogium happens once in a female Ocampa's lifetime and the talk and reference is to Kes deciding if she will have a child. There's no indication of her having multiple children, but just one. Even the episode Before and After still references one child, indicating this is a normal ocurrance.
Obviously female Ocampas would need to have at least two children in their lifetime just to replace each generation, assuming there are no accidental deaths. But these two episodes give us every reason to believe that the average number of children an Ocampa female can have is one per lifetime.
Is this addressed in any other episodes, or is it addressed any non-canon media? It'd be interesting to know how a species where the average number of offspring per female is one per lifetime can survive more than a few generations.
Note/Addition: Please note I ask if it's addressed on screen or in other media. I am not asking* if the writers made a mistake or if that was the need of the story. It's obvious that was the situation. I want to know if the poor math involved in this was ever addressed and that's what I asked.