This fanfiction concept also challenges the way the characters are perceived in the original plot. Naruto and Sasuke are seen as rivals and friends, but in this fanfiction, they are in a much more intimate relationship. It makes the readers re - evaluate their understanding of the characters and how far their relationship could potentially develop. It also challenges the gender roles and expectations within the Naruto universe as male pregnancy is not a part of the normal lore.
The original plot is mainly about ninja battles, friendship, and the search for power and peace. The Sasuke pregnant by Naruto concept diverts from that. It forces the characters to deal with family - related issues and domestic situations which are very different from their usual ninja - related problems. For example, instead of thinking about how to defeat an enemy, they now have to think about things like preparing a nursery or dealing with morning sickness if it's part of the fanfic's take on the pregnancy.
Well, in the original Naruto plot, there's no such scenario. So it completely changes the relationship between Sasuke and Naruto. It adds a whole new layer of complexity that wasn't there before.