she conceived and she bore

A chumash question- ( this is not rhetorical - i'm looking for an answer) Every time some one gives birth in the chumash it always say "she conceived and than she bore " but with Moses and Zipporah when she gave birth to Gershon it only says she bore - it doesnt say she conceived. Chizkuni says the change in language is because when she was pregnant it wasn't recognizable because she carried small . I find it hard to understand why the Torah would alter it's normal language to teach me Zipporah carried small. When thinking about it , I began to question why the Torah would always say she "conceived " how else would she bear a child? . Thats my question . Why metion everytime that she "conceived " and why leave it out with Zipporah ? Do you feel my confusion?
DAD