When it can live outside of another person’s body. Just like how no matter how much I want a kidney that you promised me if you decide that you are no longer willing to undergo surgery to give it to me, even if I’m already knocked out to receive it, you can back out. You are the ultimate master of your body, but so is everyone else.
Okay, so then you believe that a person has rights when they can survive outside of the woman. So then the humanity of a fetus depends on location of the mother because in some countries the fetus can be born much earlier due to medical technology. That is not a logical stance.
At no point is any person ever required to maintain using their body to keep someone else alive. If it’s your job and you don’t do it you may need professional consequences but never jail.
The fetus has rights but they all fall below that right of bodily autonomy.
That is what makes pregnancy a unique situation, another person is required to keep a fetus alive. If the fetus has the right of bodily autonomy, then the consensual act of making it was the consent to carry the fetus 9 months.