5. Ovarian Cancer
An analysis of 27 previous studies showed an association between the onset of menstruation and the risk of developing this type of cancer. Critical days before age 12 are associated with a 51% increased risk of death compared to onset after age 14. Scientists again attribute this to estrogen production.
6. Diabetes
A health study of 13,308 women found that those who started menstruating before age 12 were more likely to have type 2 diabetes. The link, apparently, is not direct: most likely , being overweight, which also causes earlier critical days, affects the likelihood of developing diabetes.
7. Infertility
Women with early periods tend to have a lower ovarian reserve (number of healthy eggs). In addition, early menopause can disrupt plans to have a child as an adult.