If a fetus does not have a right to life, then when does it gain a right to life? After it comes out of the womb? This implies that changing location suddenly gives a human a right to life. That’s obviously ridiculous. What about consciousness? Well we’re technically unconscious when we sleep or get knocked out, so do we temporarily lose our right to life? Surely not. Even six week old fetuses have some level of consciousness (http://www.ehd.org/dev_article_unit7.php).
Perhaps a certain level of consciousness gives a right to life, but that’s arbitrary. Why does that level of consciousness give a right to life? Suppose a person went into a coma but had a 100% chance of recovering. Surely it’s not moral to kill them during a coma. Furthermore, this implies that people with greater levels of consciousness are more valuable than others, which is clearly false. So a right to life must not come from the level of consciousness.
In fact, rights cannot come in degrees like consciousness does as the above example shows. This leave us with the best answer: We have a right to life because we are of a certain *kind* of being at the very moment of conception: a rational animal (aka being human). Kind, not degrees of consciousness, are what give humans the right to life. Since fetuses are humans, abortion is wrong.