"Sie hat nicht weniger als zehn Kinder."
It means a different thing to say "as many as ten" and "no less than ten"/"no fewer than ten". "no less than ten" is equivalent to "at least ten" not "as many as ten"; "as many as ten" is an ambiguous expression that is usually employed to imply that "she has just ten, but ten is a relatively large number in the context."
First of all there are some communities where ten children is a basic thing. Second, I think it should be accepted. As you can see, this is the average: http://en.wikipedia.org/wiki/List_of_sovereign_states_and_dependent_territories_by_fertility_rate average = some have more....
I did say "in the context" (of the speech), so what you've mentioned here is irrelevant. Also, your concern is irrelevant in general, since it is a linguistic matter, and in the English language, "as many as ten" is a different expression to "at least ten", and to translate "nicht weniger als", we use the isomorphic phrase "at least ten", instead of an interpretive phrase that may cause implicative ambiguity.