The Foster article reports that as contraceptive use became more widespread in the developed world from the 1990s to the 2010s, the number of abortions significantly declined to historic lows. She argues that the unmet need for abortion is largely due to the fact that many of the women who do not use contraceptives cite their low perceived risk of pregnancy, opposition to side effects, and to a lesser extent, are morally or socially opposed. To make no political argument, Foster glosses over the latter group, which I believe if they were opposed to contraceptives they would probably also be against abortion.
It's very interesting to me that there seems to be no agreement on the socio-economic factors responsible for the inverse relationship between education and fertility. A number of studies were performed on factors that I would've thought to affect fertility (probably because that's what I was taught in undergrad), but there was no consensus. Apparently things that are intuitive (to me, at least) like opportunity costs of childbearing and Western influences are difficult to support at broad levels.