It's a woman's right to decide what happens to her body, which includes having a baby. Therefore they can chose to not have a baby. Therefore abortion is fine.
Also, because there is not scientifically agreed upon age of development at which a foetus becomes a human, you can't say that abortion is murder because you can't prove that a feutus of any age is technically human.
The fundamentals of Kantian ethics are flawed. Kantian ethics bases its system on not paying attention to the consequences of actions. But the Categorical Imperative (a key part of Kantian ethics) asks us to justify actions by using the maxim 'Only do that which is universalisable' that is, actions are only moral if everyone could do them all the time. This part of Kantian ethics offers a direct contradiction, as considering universalisability surely pays attention to the consequences of actions.
Kantian ethics pays no attention to the consequences of the actions they do or do not take. But the rest of our lives are based on consequences. Systems of learning, how we know things and so forth. Paying attention to consequences is inherently part of human nature, and so we shouldn't build a system of morality (such as Kantian ethics) that is not based on consequences.