This debate has veered onto when life starts and has illogically mixed the purely legal concept of 'rights' with the emotional response to death. Nature needs death to allow life (even conception requires millions of cells to 'die' to allow one cell pair to comingle genetic information.)
Abortion is a natural process. Nature affords no rights beyond one chance to live. Mankind has learnt to respect that process and has shown that respect by deciding (with caveats) when humans die (we build hospitals and bombs.) When resources are scare life is valued less and when resources are plentiful life is valued more. By projecting our personal desire to avoid death onto others we forget , as Razz. brilliantly pointed out, that our value to society is weighed and measured and found to be valued in a few dollars. Your life is worth less, to society, than a basic tv. The debate about abortion is simply part of the wider debate that sees billions die from lack of food, water and medical supplies - the famine starved child is selected for death just as surely as the second trimester unborn child.
We are animals. Animals kill their young when needed. Nature is ammoral. We may legislate against murder but it is merely a facade to pretend we aren't animals - we are all murderers with respect to those that die that we may eat at McDonalds and wear diamond wedding rings. Abortion shows respect for our true nature (we show a mercy that nature would do at the hands of a predator or natural abortion by killing the malformed unborn , we show resource judgement by terminating another life in a resource low household, we show mercy by murdering the unborn offspring of parents who are not committed to each other and/or are parents through violent rape.)
Abortion is such a harrowing event- regardless of whether it is through nature or choice - that it is not made lightly. This debate is the woman's alone, should she choose to share it with a partner, family or friends is her choice. She bears the entire cost of the process physically. Her body is endowed by nature to start and stop life every month and each stage of that process considers life (at the cellular level) as purely a resource and terminates all cells involved until conditions are exactly right and implantation is allowed. even at this stage the body views natural abortion as a viable process (therefore from a scientific pov it is moral) to either remove malformed cells or abort the fetus in times of trauma(famine, extreme fight/flight experience, violent damage, infection, poison from such things as alcohol.) Nature (or god for the magically inclined) cares not about pain or viability as a non-parasitic human and will abort life according to circumstance either through misfortune (e.g. cord strangling), need (e.g. many animals eat their offspring when hungry) or genetics (my wife for example cannot carry boys and so we chose to keep having children in the knowledge that she would gentically abort any sons.)
It is perfectly scientifically moral to allow elective abortion to help natural abortion do its job of maximising the overall fitness and potential of each species to pass on its genetic material. Nature is the main user of abortion.
As soon as a child is independent from the mother some enlightened societies (normally those that have already entrusted women with other important legal rights) also afford it society rights (a recognition that the responsibility for that person is now shared between mother and society whereas before that person was entirely the mother's responsibility.) At this point laws designed to protect society are valid (for example - no murder - oddly enough this rule is NOT to protect the individual!) since that child is now a productive member of society (whereas before the unborn child is not.)
So abortion is absolutely moral.
Itshould be enshrined along with other rights for women in law.
The religious need not fear since not only is their magic person an abortionist but their legal right to self determination are re-inforced by the above. Should they wish to take away the right of another person to decide what happens to their body then they have given away the moral argument for society to protect their religious rights and open the door to a society where abortion could become a legally required procedure (if overcrowding was an issue for example) which should scare the cr*p out of them. Taking away self determination rights is a very bad idea.
imo.