It was normal back then, so not really an issue, 14 year old girls had nothing but motherhood to look forward to and on average they only lived till their 30's, so the once they started their period they were ready to be plucked.
Actually, Richard's right that Shakespeare never wrote this line. I just did some research. It's improperly attributed to him. As for whether he'd ever have written anything like it, I dunno. Shakespeare could be pretty blunt at times.