What is "pendant natural" in this UN report?

Unless the author is using a Spanish or Portuguese expression, it's a typographical error in the French pendant naturel, meaning ‘natural counterpart or complement’, i.e., that discussing one topic will naturally lead to another. An NGram suggests it is a not uncommon expression in that language.

Le pendant naturel de la lutte contre le racisme est le dialogue interculturel qui est une des composantes essentielles …
The natural counterpart of the fight against racism is intercultural dialogue, which is one of the essential components …

Without looking at the French, an English speaker would likely say “a natural extension.” Same idea, different spatial metaphor.

Per Merriam-Webster, one meaning of "pendant" is "counterpart" or "companion piece". So in this case, the text seems to be saying "[the sharing of parental responsibility] is an issue that will naturally be considered alongside [whatever issue they were talking about before the quoted text]".