This is an incorrect phrasing of the situation. The actual question is what moral principles do we already accept? Which ones are more fundamental than others. Instead you are literally affirming the consequent by presupposing that bodily autonomy is morally relevant.(Otherwise,if that’s not what you are doing,your phraseology is just bizarre)
Laws force people to use their body regardless of how they feel about it. We agree that it is moral.
Prohibiting abortion is denying the ability to perform an action. We assert that this is immoral.
However, forcing an action is stronger than denying an action. So which premise is wrong? Is it the one that leads societal rules unenforceable, or the one that makes a quarter of the population temporarily unhappy?
There is also the extrinsic teleological argument that pregnancy isn’t a violation anymore than your pancreas producing insulin. A belief can be irrational if it contradicts a biological function.
“Would a fertilised egg be human”
As long as it is a separate entity that is living and functional with a probability of future conscious experience. Note, that I don’t make the unique DNA distinction because that would render killing clones permissible.
Now unlike some people I don’t think that all abortion is immoral, just one’s where we have a reasonable expectation of future human experience so long as we do not take action to reduce this expectation. Like how rendering someone brain-dead so you can kill them is just a more elaborate active killing , something like drinking alcohol to render your fetus brain dead is also active killing.