There is not such a rule
Also I’d like to know why you are pro-life (just curious)
I could yack your ear off for an hour explaining why I’m pro-life (and have done so many times as it seems so strange to so many people that someone who doesn’t believe in God would be pro-life).
In essence, I’m pro-life because I believe in equality and the value of individuals. I stand up for fetuses for the same reason I’d stand up against abuse of the elderly: because the less vulnerable owe it to the vulnerable to do
something.
Arguments to choice do absolutely nothing to persuade me, due to my belief in the equality of worth of every individual. A fetus is not an extension of the woman bearing her, nor is she a parasite, as some rather morbid pro-choicers have said in the past. She is an individual human being equally deserving of life as you or I, or the mentally retarded, or the encephalic, or the demented, or the elderly, or the most recently born.
I’m quite aware of the utter dependence of a fetus on the woman bearing her, but I’m not convinced that dependence is a disqualifier for so-called “personhood”, otherwise the same argument to “choice” ought to apply to infanticide, or the passive euthanasia of the elderly and infirm.
Now, I’m open minded when it comes to pro-choice arguments, should any good ones arise. The most common objection I hear always seems to in some way involve distress or inconvenience placed on the pregnant woman. Again, distress and inconvenience doesn’t seem enough to me to deny life to
another individual. Even in the most brutal of cases, which to me seems to be the rape of a woman who subsequently becomes pregnant, I cannot fathom how psychological trauma and/or distress of having to give the baby up for adoption
outweighs the interest of the baby to live. And to be sure that I’m consistent in my ethics, I would graciously
cause psychological angst and emotional distress in 100 people if it meant that doing so would save the
life of just one.
There’s more to be said, for sure, but I think this suffices for now. I’d be happy to answer questions if you think of any.
Cheers!