Abortion is unethical because it is denying a future human a future
Killing is wrong because it deprives an individual of their future, a future they were looking forward to. A fetus can be expected to have a future, and ending its life would deprive it of that future. Therefore, it is wrong to terminate a pregnancy. A fetus can be expected to have similar experiences to an adult, and terminating a pregnancy is akin to the premature death of an adult. Both things deprive an individual of a future, making both things morally wrong.
An adult human has the ability to look forward to their future and plan out what they would like it to become. A fetus, on the other hand, does not know what sort of experiences they could have, and they do not have the ability to plan out a future. As that is the case, a fetus is not aware that they are being deprived of anything when a pregnancy is terminated, the same way an adult is. Another counter to the argument is that it allows abortions in too many cases. If a fetus cannot be expected to have a similar future due to a disability or because it will be born into horrible living conditions, then aborting the fetus may be acceptable according to this argument. That is not acceptable, because abortion should always be wrong.
[P1] All persons have futures. [P2] A person's future is of value to them. [P3] Depriving a person of their future is wrong. [P4] A fetus can be expected to have a future like ours.