Before revision: The average age of menarche dropped from 14-15 years to 12-13 years since the nineteenth century , but it seems that girls in the nineteenth century had a later age at menarche compared to girls in earlier centuries.
After revision: The average age of menarche dropped from 14-15 years to 12-13 years in the presentin the nineteenth century , but it seems that girls in the nineteenth century had a later age at menarche compared to girls in earlier centuries.