subordinate clauses - Rules for pronouns

Is there a rule in English regarding whether a pronoun or the subject it refers to should appear in the subordinate clause of a complex sentence?

1. Simple example: “Whenever the little girl/she eats pizza, she/the little girl gets sick.”

Should the pronoun she or the subject the little girl appear in the subordinate clause? Is one choice wrong or is this a matter of taste and style?

2. Complex example: "In the form that the history of literature/it took as it emerged out of the historicist culture of the nineteenth century, it/the history of literature tended consciously or unconsciously to imagine series of works and cultural periods in terms of a perpetual metamorphosis or a permanent revolution."

Should the history of literature or it appear in the first clause?

3. Is there a rule about this in English? If so, how do I describe it in grammatical terms?