Elizabeth Gregory was interested in the fact that in 2005, ten times as many women had their first child between the ages of 35 and 39-years old, as did so in 1975.
So the director of the women's studies programme at the University of Houston, set out to ask these women what their experiences of so called "late" motherhood had been.
And the word that popped up time and again in her interviews with them was "ready."
Older women felt ready to have children.
And they were consistently positive about their decision to wait.
As Elizabeth Gregory says "these new later mothers live in a very different world from the one the media portray."