I'd be interested in deeper study.. widows v single career women v divorcées and a relation to loss of child bearing ability personally v children who choose si.gleness resulting in no grands...
I suspect we'll find the greatest incidence among unmarried cat ladies who suddenly realize their greatest reason for being (bearing children) will never be realized, and the lowest incidence among widows who have grandchildren in a close family. Married postmenopausal women with no hope of grands may actually eclipse widows with grands... just a hunch..