How about FEAR? Fear of economic insecurity - of providing for oneself, one’s children (born or unborn), one’s parents, encompassing education, health care, living income and job security, retirement, public safety services. Fear of social stigma - despite cultural advances in the acceptance of public pregnancy, it still invites looks, questions, and complications to be a pregnant student or business professional, and if you are in a position dependent on your looks, size, or athleticism (model, actress, cheerleader, airline stewardess, even many wait staff and retail sales), forget about keeping your job.
I think many pro-life conservatives want to eliminate abortion through legislation and and restricted access - basically, trying to reduce supply. Many pro-life progressives believe in eliminating abortion through eliminating its causes (fear and perceived necessity) - basically, trying to reduce demand. We need to work on both simultaneously.
If we reduce abortion supply without reducing demand, the cost of that choice goes up. I’m not just talking about the price of procuring an abortion (which would increase, either because the abortionist can charge more for rarity or because the procurer must travel farther or jump through more hoops to do so). Costs to the individual go up in terms of personal safety (think back-alley), and costs to society increase as we have more children growing up in families and communities insufficient for their needs. Then those emerging adults are less able to contribute to a growing economy and more likely to perpetuate a cycle of under-educated, under-employed, dependent parenthood.
If, however, we improve the economic security of individuals, families, and communities in sustainable ways (education, preventative health care, public safety, living-wage job creation, environmental protection, greener energy and community infrastructure, etc), we create a society that is less toxic to parenthood. Couple that with increased societal messages that a fetus really is a complete human life that deserves protection, and abortion demand will dwindle. If a pregnant woman is looked upon not as a whore to be shamed but a heroine to be championed, she will have little reason to kill her child.