When I imagine a selfish person, I picture someone who cheats, or steals, or behaves in some other way that benefits herself at the expense of others. So why, I wonder, is “selfish” so frequently used as a weapon against child-free women? Not procreating doesn’t hurt anyone, especially not the non-existent child(ren). Who is losing out in this equation? The “community?” The partner who must want an heir? The sad and lonely non-grandparents? “Selfish” does not merely mean, “cares about ones self” or “acts according to ones own desires.” The “…with disregard for others” is part of the denotation.
But perhaps, when applied to women’s reproductive decisions, “selfish” has a separate connotation. Perhaps doing what you want, period, is bad, destructive to the community, and deserving of scorn. Although that does not seem to apply to straight, able-bodied white women who want to have children – most all of whom do so to fulfill some personal desire that could qualify as “selfish” (in either sense of the word).
My guess is that the busybodies who accuse child-free women of “selfishness,” having not thought about it too deeply, are simply going with an attack that (they believe) will hit women where it hurts. Women are supposed to be selfless and obedient, not following their own paths. Accusing a deviant of “selfishness” might snap her out of it and convince her to make babies, or it might inspire her to ask, “wtf?” and write about it.