Question

What percentage of 40- to 44-year-old u.s. women remain childless?

Answer 1

increased from 10% in 1976 to 20% in 2006
These type of women usually choose not to have children on their own due to time (if those women choose to not have children in order to pursue a certain lifestyle or career)  or genetic factors (if those women had a physiological condition where they can't have children or having one will expose them to a certain amount of risk)