Age of Eighteen Hundred brides

I have just uncovered an ancestor who was married prior to her 12th birthday in the early eighteen hundreds. My genealogy software keeps giving a warning on this record. It seems many women were married around 15 or 16 years old during this time. This is the first one that was so young, but I know that it happened in Appalacian Mountains even up to the 1900's. I have not ordered the films yet to check for the accuracy and whether this is the right family, but has anyone else run across marriages where the bride was so young?

Maureen Bejar