It depends on whether a person is doing it as an interested family member, to help out (as in the stories of grandmothers who bear children for daughters), or if the person wants to do it for a fee. I believe that in general in the latter case, the IVF doctor will have some limits (set by the clinic) for the age of the gestational carrier. They definitely have age limits for the prospective mother (even if she is not going to carry the baby), and I think the age limit a clinic I'm familiar with uses for potential gestational carriers who will be doing it for a fee, is 30 years old. Not sure, though.
Actually I think that as long as the doctor ok's the persons health and they are able to carry the child I don't think that the age matters there was this older woman who actually carried her grandchild for her daughter and she was in her 50"S
I do not think there is an age limit to be a Surrogant. You hear of mothers carrying babies for the daughters sometimes... and they are in their 50's or so. Nancy Grace was in her 50's with her twins.
Hope this helps