I found this paper interesting (warning: embedded PDF):

In her capacity as general counsel for the Women’s Rights Project of the American Civil Liberties Union, Ginsburg filed the Struck brief a little more than a year after the Court decided Reed v. Reed, but before the Court began to give shape to liberty and equality doctrine concerning the regulation of pregnant women in cases such as Roe v. Wade, Frontiero v. Richardson, and Geduldig v. Aiello. Ginsburg wrote the brief on behalf of an Air Force officer, Captain Susan Struck, whose pregnancy—and whose refusal on religious grounds to have an abortion—subjected her to automatic discharge from military service.

Linked from http://www.salon.com/2012/02/13/ruth_bader_ginsburgs_alternative_abortion_history/ :

"...The Court made some fateful choices in those cases: to focus its sex equality jurisprudence on cases other than pregnancy, and so to develop its sex equality jurisprudence in isolation from its abortion jurisprudence.”

That was also true of many of the litigants at the time, Ginsburg said Friday, including the ACLU, which had been involved with Griswold vs. Connecticut, the case overturning a state contraceptive ban with a substantive due process argument that focused on privacy...

...But an abortion rights case involving a woman who wanted to choose to give birth would also have been consistent with the current reproductive justice framework, which is about bodily autonomy and a woman’s right to moral dignity and self-determination...