She was interviewed on Woman's Hour last week.
Looking at it one way, I suppose she could be compared to a grandmother or elderly aunt who had to step in if the birth parent died.
As a fit 64 year old, her life expectancy is around 90.
Generally, I am fairly liberal about mother's ages because there are so many children being brought up in other circumstances that are far from ideal, often with very single young mothers.
But knowing that you are pretty likely to die before your child reaches 35 is quite selfish, yes.