What are the three objections to surrogacy from the surrogate mother's perspective, and how strong is each?
(1) It violates her dignity, (2) she is exploited, (3) she is reified (reduced to a womb). None justifies a ban in principle: dignity is respected if she gives valid consent, and exploitation and reification depend on the pay, the working conditions and how the arrangement is designed.
* Each objection turns on consent and circumstances rather than on surrogacy as such *
(1) Dignity. Draws on Kant's ban on instrumentalisation (using someone merely as a means). But it is hard to pin down what that means: a cleaner who cleans other people's offices also uses her body for money. Is she instrumentalised? Counter: pregnancy carries a far greater risk to bodily integrity, closer to organ donation. Working assumption: no violation of dignity as long as she consents (self-determination is preserved). But consent can be hollow: in India some contracts were only in English, which the women could not read, or the women were illiterate and relied on oral information; and poverty may undermine a qualified consent.
(2) Exploitation. "Exploitation" as unfair advantage-taking has two conditions: (a) the exploited person gets an unfairly low benefit or carries unfairly high costs, harms or risks, and (b) her consent is incomplete or invalid. So it depends on the circumstances: pay and working conditions, especially safety and health protection. By appeal to human dignity, certain minimum standards must hold even where local standards are lower (in India, surrogates were housed in rented flats without basic sanitation for fear of stigma). The worry that high pay lures women into it would not be raised against other jobs such as cleaning or delivering newspapers.
(3) Reification (Verdinglichung): she is reduced to her function as a womb, which denies her autonomy and thus her dignity. It can be prevented by shared parenthood in which intended parents, child and surrogate all take part.
Go deeper:
Stanford Encyclopedia of Philosophy: Exploitation — the unfair-advantage and defective-consent accounts of exploitation.- Wikipedia: Surrogacy in India — the commercial-surrogacy context behind the consent and conditions worries.