The "Ocampa females can only have one child" thing is as much in the eye of the audience as it is in the typing fingers of the writer. Or, probably, more in the former.
What the episode establishes is that in order to have kids, the female must respond to the call of this eloqium, and that if she doesn't, that's the end of it. What it never establishes is what happens if she does. So you either choose to be a child-rearer, or then you choose against it. If the former, many happy birthing events to you, supposedly...
It's virginity in reverse, is all, in the not particularly misguided mind of the writer. If you choose not to lose it that one time, you will go childless for life. Intuitive, intriguing - and fine writing, really.
Timo Saloniemi