A woman is only excommunicated if she does not repent and ask forgiveness for the abortion. A woman’s “punishment” comes with the loss of her child, and she lives with that for the rest of her life.
And there are so many pro-life groups that reiterate the woman is considered a victim in abortion. You do realize that Planned Parenthood, for instance, does not tell the mother-to-be the side effects of an abortion. Nor is she provided an ultrasound with the image of her baby prior to the procedure. Imagine going in for a valve job on your heart and no one tells you what might come of it. Everyone should be told of the potential for a broken heart.
And I’m not familiar with polls being taken on this subject matter. But here is just one pro-life group out of hundreds with their explanation:
http://marchforlife.org/no-pro-life-american/
Assuming you're referring to the Catholic position, this is false. Women are automatically excommunicated the moment they commit or cooperate with the abortion. Popes have ruled that they can only gain forgiveness through their Bishops after penance and confession. Catholic concept of penance is not simply feeling sad, but actively taking steps to "right the wrong."
Whatever the case, the entire logic disproves the "All pro-lifers think women are blameless because women never understand what they are doing when they commit an abortion." If they're guilty of a sin, then they, by definition, are not blameless, and clearly the act of the abortion is not enough to absolve their punishment. The EO and other denominations follow the same logic, with pro-lifers, like Tony Miano, concluding appropriately about the fault of the mother:
http://crossencountersmin.com/featured-article/abortion-yes-murderers-should-be-punished/
Tony Miano is protestant, but quite clearly calls it a sin and states women should be liable for punishment.
Similarly, this Catholic, Trent Horn, from Catholic-answers, also argues for the punishment of women for abortion:
http://www.catholic.com/blog/trent-horn/should-a-woman-be-punished-for-having-an-abortion#_edn1
Although he recommends punishments as light as 1 or 2 years, and that punishment, like for any other crime, should be a case for case basis. He also reframes the argument from, "Should women be punished for having an abortion?" to "Should men and women be punished for killing their children?"
So, do Pro-lifers at large support this idiotic logic put forward by these people purporting to represent pro-lifers? No, not really. I've also seen the same reaction among pro-life groups across the internet, all favoring the punishment of women for breaking the law if abortion is made illegal.
There are no polls demonstrating this, but more than likely, more than half of pro-lifers side with this view, and the only people who don't are the Cruz supporters who have only discovered this issue over the past couple of weeks.
A woman’s “punishment” comes with the loss of her child
This is like saying, a woman who drowns her children in her bathtub is punished by watching them die.
You do realize that Planned Parenthood, for instance, does not tell the mother-to-be the side effects of an abortion. Nor is she provided an ultrasound with the image of her baby prior to the procedure.
This is entirely irrelevant since if a woman knows it is against the law to have an abortion, whether she appreciates that her unborn child is a child, she clearly knows she is breaking the law and, thus, should be punished. Furthermore, even ignorance of the law is no basis for being spared punishment from the law.