the woman is always the surrogate.
Indeed - although I have seen an Dr Herjeet Marway, Director of Philosophy from Birmingham University who chairs on the Surrogacy U.K. ethics board say it's "usually a woman".
"Gender
Ethics also come into play when thinking about the gendered nature of surrogacy and intended parenting. Biologically, the surrogate has to be someone with the capacity to gestate and give birth – usually a woman. As gendered labour, surrogacy triggers important feminist concerns, such as about bodily autonomy, vulnerability, inequality and rights."
I don't know who else it might be, usually a man I suppose. Goodness if it was, wouldn't this be an entirely different landscape!
I always say surrogate mother because we all have mothers, even if just for 9-10 months on the inside, even if only for a few minutes on the outside. We all have a mother and the trans men erasing it from their child's birth certificates, or the gay men raising their adopted children, telling them they don't have a mother, or the maternity and breastfeeding services using 'birthing parent'...or the gay men 'using' a woman...they can all get to fuck as far as I'm concerned.