I'm totally pro-life (but I think abortion should be legal in the first weeks if it was by sexual assault or any health issues with the mother), and I have many arguments against abortion.
First, those who are in favor because it'd be cruel to let a baby live a poor and miserable life, it's just wrong. It would be like justifying mass infanticide around the world just so they would not live miserable lives. Wether the baby will grow up poor or not is none of your business, you can't just deny its right to live. It's extremely wrong to decide someone's right to live based on economic background, like just letting rich people reproduce.
Those who are in favor because of fetal defects, it'd be just like in the ancient times when babies born with defects were killed. It's just like harvesting children based on superficialities like appearance. Again, you cannot deny them the right to live, because it's their right, none of your business again. The idea of harvesting children is just as wrong and comparable to many of the naz1 ideologies, like attempting to reach a pure race of certain people and killing all the weak or sick people in the world.
Those who are in favor because it's the woman's right to choose over its own body, let me remind you that wether or not you think that a fetus is alive or not, it still feels pain, has a heartbeat. Isn't it enough to classify it as life, and thus a different individual for you? Most of its body parts have grown by the 12 weeks. It does not have the same genetic material as you, so it isn't a part of you. It's an individual life you should take care of. It's not your decision what should happen to the baby as it's not your body.
Let me remind you some few things people have probably forgotten over the time:
They say it's none of a man's business to decide about women's body. First off, some genetic material from the father is in that baby, so it's not completely the woman's baby, so it should not be only her decision to do an abortion or not (hypothetically speaking that abortion is ethical). Also, let me remind you that abortion laws were, or at least in many western countries, promulgated by rich and privileged white men. If you say it's none of a man's business, then abortion laws around the world must be repealed because it was men who promulgated them.
At the end, (just like in the abolition of slavery in the US) people who make laws often don't care about people's rights, but just business. Slavery wasn't abolished because they thought it was unethical, but because it was not profitable anymore. At the end, abortion clinics are still businesses who want money and power. In abortion centers, the amount of money they charge you is based on how big the baby was at the moment of the abortion. Does it sound like they at least minimally care about "women's rights"? If they cared, they would invest more in controlled pregnancy methods/surgery, sexual education for everyone, etc. rather than just telling you to abort, thus earning more money. They would at least talk to you about the risks, pros and cons, and procedures of an abortion, which they just don't.