Would John Stuart Mill support reproductive freedom?
I believe Mill would have supported reproductive freedom, since his support for the equality of women in all spheres of life, including business, intellectual pursuit, religion and social relations indicated his belief that women (indeed, in Mill's view, all people) should be able to stand on their own, without the patronage of men or institutions. Mill's treatise The Subjection of Women (which Mill claimed was co-written with his wife, and perhaps even his daughter), lays out the notion that women historically had been little more than slaves to men, and should be emancipated from that condition immediately:
"That the principle which regulates the existing social relations between the two sexes — the legal subordination of one sex to the other — is wrong itself, and now one of the chief hindrances to human improvement; and that it ought to be replaced by a principle of perfect equality, admitting no power or privilege on the one side, nor disability on the other."
Mill believed that a woman's life, including her body, should belong only to her, to be used as she saw fit to earn an income, enter into marriage, or produce children, without censure from religious, societal, or male influence, so her retention of reproductive abilities aligns with that overarching principle.