My friend is a Midwife and she didn't offer much explanation, but says that a young persons pregnancy (13 to 19), is 'high risk'. I understand the U15 category's, however, at 16+ a woman has no reason to have any more 'high risk' assumed complications than a mother of 22.
At 16+, your body would have no issue doing what it's suppose to, so why is it categorized as high risk? If anything, younger mothers seem to labour much easier and quickly than those a little older.
Yes, I am aware that U21's are at risk of preeclampsia.