Reproductive rights were certainly a factor, but the big impetus for the shift in politics came from Betty Friedan and The Feminine Mystique. Before then, reproductive rights were subsumed under other issues (politics made for odd bedfellows back then as both Progressivism and the eugenics movement embraced legalized contraception). For the first time since the 19th Amendment was ratified, issues of gender replaced issues of class and economic status in women's political identity -- due in large part to Friedan (and others who didn't get published) wanting to be more than just a wife and mother.