All those who force a woman to have an abortion -- her school nurse, her doctor, her friends, her boyfriend, her lover, her husband, her mother, her mother-in-law, etc. -- should also be held criminally liable. Studies have shown that many girls and women are forced into an abortion. Those who are forced into an abortion should not be held criminally liable. Instead, those who conspired to kill her and/or her unborn baby should be prosecuted.
Rarely is a woman "forced" to have an abortion; that's usually after-the-fact rationalization from women who subsequently developed guilty consciences about it.
Pressure? Yes, I'm sure that happens all the time. But forced? I'm sure that happens from time to time, but it's much more rare.
In any case, you would treat this like any murder case. If these other people (e.g. men) materially participated, then they should be tried as accomplices. If they tried to persuade her to do it, they could be accessories or conspirators in murder. If a woman were forced to such a degree that it was no longer a free act, then of course she could be found not guilty. But, despite the outward fear and pressure, sin is still sin if there's any element of free will left. So, for instance, those who apostasize under threat of death or torture, still commit a sin; it's merely that the gravity of the sin in God's eyes may be extenuated due to these external pressures.