I agree with Jeb Bush that immigrant women are generally more likely to bear larger numbers of children than are today's American women. That statement is a general observation and is not contradicted by anecdotal evidence as to individual American women or individual immigrant women. How does that make me uninformed?
I believe the term “fertile” is being used as a euphemism for “having a lot of children per family”.
The “ignorant” part is trying to apply the actual definition of “more fertile” to the groups in question -
it’s not correct to say, in actual definition, that immigrant women are “more fertile” than American women, when the definition is “ABLE to have more children”.
Any highly developed society or culture inevitably has a lower birthrate out of choice, whilst a 3rd world (where immigrants come from) culture will have a higher birthrate.