Well, first off, abortion activists don't agree that life starts at conception. My proposition is that even if we assume that life begins at conception, it should have no impact on restricting abortion. There is a difference between life and personhood. Your skin cells, bacteria, and viruses are technically alive.
Secondly, the choice is the woman's because it is a medical decision. In this country, we have legally protected rights to privacy and individual autonomy. Reproductive rights are predicated on those two principles.
The woman's rights should trump a fetus's rights. The end.