I hold the controversial opinion that abortions need to be safe, freely accessible and without moral or legal prohibition, like any medical procedure. There are many reasons for this, foremost related to the United Nations' declaration of universal human rights.
The human rights are predicated on the right to human bodily autonomy. Even the right to life is less important than the right to have control over your own body. A dead body may not be used to save lives without the consent of its previous owner or their next of kin. That's how it works in virtually all places; in the spirit as well as in the letter of law. That's how it has to work until we develop a system of law that actually values life, beyond seeking to disincentivize those who take it from others.
It follows that a mother's right to her own body supercedes the right - maybe, at some future point - of her fetus to live. Medically speaking the fetus is a parasite; legally, an invader. It doesn't have the right to its mother's body. And even if it did, the mother had it first. And even if she didn't, she's the adult in this relationship. She has to be the one who decides for her body.
That's all there is to it.
But then there's a lot of religious and moral arguments against legal abortion, the most reasonable of which boil down mostly to personal beliefs about how women need to be punished for having sex the wrong way that neither can be used as a basis for law nor do have anything to do with children. Here's a thought experiment I remember about that very point.
Let's remove the complex, contentious topics of sex, sexes and genders from the equation to clarify what the issue is specifically. Let's say a person can make another person pregnant by zapping them with a ray gun. You can be walking down the street and zap, someone decides to make a baby with you.
It doesn't matter what you wanted, how responsible you were. It matters that now you have a baby and you need to face up to your responsibility. And besides, good boys and girls don't walk on the street with strangers. You knew there was a chance you could get pregnant and you did it anyway. Would you like to end your pregnancy? Well the father wants his baby, and the baby presumably wants to live, so it's two against one. What, now you want some say in what happens to your body?
Gee, if only there was some way to stop a pregnancy before it was too late. Like a safe and not very demanding procedure to remove the fetus from your body that a doctor could do within the day. You know, while it's still a lump of cells as capable of autonomous life as a scoop of menstrual blood. And then maybe you could still have a child at some other point when you're in a better position to do it.
Timing is tricky. It can be very important and very easy to get it very wrong just with very small mistakes. That's why it's so good to have safeguards to give us some measure of slack, to minimize our suffering. Especially in something as important as our reproductive cycle.