I see nothing wrong with the sentence. I'd use "as they grow," or "while they are growing up." "As they grow up" is possible, but might be confusing to some, since we use the expression "when they grow up" to mean "when they attain maturity," and the expression "you'd better grow up" to mean "act like an adult."
Logically, you might argue that if the process is hindered, the sense of