Vegan views on Abortion
Abortion is a contentious issue, not only in the United States but much of the Western world, and while much discourse is political in nature and entails much rhetoric and frankly ignorance, it's still a huge topic for those educated in ethics.
Note that there isn't a "vegan" position on abortion, just like there aren't vegan positions on anything that isn't related to animal ethics. Asking what the Vegan position on abortion is just as incongruous as asking what the Biologist position is on relativity. You will find vegans of all types with differing views on the matter, each with different motivations and reasoning; Many vegans who have a basic grasp of ethics, who used their understanding to arrive to their position on meat consumption will also use it to come to a position on abortion, and this varies amongst the different ethical schools (consequentialism, deontology), and even then, within these ethical schools there are various schisms abound on the topic, just as there is for every Vegan issue.
Through a consequentialist standpoint that considers the preferences of sentient beings, while the fetus may have a small level of sentience and therefore some degree of preferences, the preferences of the mother carry far more weight due to her higher levels of sentience.
This is also a reason why the "My body, my choice" defense made by Pro-choicers is rather ignorant of the actual arguments against abortion; Pro-lifers don't accept this claim, because as far as they're concerned, a pregnant woman has a living being inside of her that is deserving of moral consideration. Of course, Pro-lifers ake fallacious arguments too, failing to establish a moral and cognition gradient and automatically assigning moral value to the fetus just because it's alive. That's sort of the mistake that some of the less rational Vegans make, thinking all animal abuse is equally bad, equating killing an ant to the killing of a pig.
Pro-lifers also have to content with the hypocrisy of supposedly valuing life, yet continuing to eat meat. If you place so much value on a fetus, why don't you place it on the animals that are raised for food?
Do fetuses feel pain?
As far as we can tell, fetuses do not feel pain before the third trimester, which is give or take 27 weeks into pregnancy, and it's possible that it wasn't even sentient before that point either.
Anti-abortion Laws
Banning legal abortions doesn't reduce it all that much, since the vast majority of women who want abortions will just get one from a less than reputable source. You aren't getting rid of abortions when you outlaw them, you're getting rid of safe abortions, and are endangering the life of the mother, a being with a VERY high level of sentience. The old jokes about a coat hanger in an alleyway exist for a reason, folks. Therefore even if it were unethical to get an abortion, outlawing them not only does not solve the problem, it just makes matters even worse and causes more suffering. If you're really gung ho about getting rid of abortions, the best treatment is often preventative. Encouraging safe sex practices and birth control would go much further in making sure that women don't need to get abortions.
Also, banning abortions doesn't address underlying problems. We need to ask, why are all these women getting abortions? The most common motivation is financial, and women in poverty are more likely to have unintended pregnancies, so therefore, it makes more sense to fight poverty than fight abortion if you really want to reduce them, not to mention it would go pretty far in helping stop other problems caused by poverty.
Another common reason for abortions is that the mother (and also usually the father) are not prepared to have a child, possibly due to psychological stress, which would be a common symptom amongst younger women (most abortions are received by women under the age of 30). If parents are not prepared, emotionally or financially, to have a child, bringing the child into the world is not doing it any favors.