If the government has the ability to regulate what you do with your womb, *ALL* bodily autonomy rights are on the table for them to devour now.
The problem with this line of thinking is that although the uterus is part of your body, the fetus inside it is not part of your body. It is a separate entity with its own body that happens to be inside your body. Since the fetus is a separate entity, this opens a host of questions regarding what rights it might have, when those rights are granted, and how to weigh those rights against the woman's.
It's also difficult to say that the fetus violates your bodily autonomy, since you essentially invited it to take up residence in your uterus by having unprotected sex. Even if we ignore this and say that the key issue is that of bodily autonomy, you have to weigh the woman's right to bodily autonomy against the fetus's right to bodily autonomy, as having an abortion will kill it, and killing its body violates its bodily autonomy. If you claim that the fetus has no such right, yet once it's born, the baby
will have that right, then you must establish a rule to determine when the fetus gains bodily autonomy rights, since your claim is that it doesn't have them from the beginning.
These problems are messy, so I think a much cleaner approach is to avoid the topic of bodily autonomy and instead focus on the topic of parental consent. If a fetus has a right to life, that right must have been bestowed by its parents, as they made the choice to create it. If a pregnancy occurs when both parents did not give consent, either because of contraceptive failure or because of rape, then it would follow that the fetus does not have a right to life, because both parents did not create it on purpose. As such, we could conclude that they have the right to kill the fetus, since they never gave it the right to life by consenting to its creation.
This seems like a much cleaner rationale to me as to why abortion must be allowed, as compared to the messy business of trying to weigh the bodily autonomy rights of two different parties. If you establish that the parents have the right to decide whether to have children and to stop the process of an unintended pregnancy as a result, then the bodily autonomy problems are automatically resolved: the fetus never had any rights to begin with, because both parents didn't consent to its creation, so killing it is permissible. Since it's impossible to prove that a pregnancy resulted from contraceptive failure and not unprotected sex, abortion must be allowed for everyone.