1. The Gen 3 passage states that childbirth pains will 'INCREASE'--NOT 'come into existence'...therefore, pain in childbirth was there before the FALL...the effect of sin was to INCREASE it...[assuming, of course, the Genesis reference is to physical pain instead of something more like 'sorrow'.]
2. Similarities between humans and animals actually can be used as a piece of evidence for Intelligent Design...if a 'stomach' works, then why wouldn't the Creator 'use it again'? in other words, an EFFICIENT Creator would be EXPECTED to 'reuse' blueprints in various species...similarities could JUST AS EASILY point to a common creator, as it COULD point to a common evolutionary process...the issue of evolution vs. creation would need to be decided on OTHER grounds...
hope this helps...glenn