10 Oldest Surviving Documents Of Their Type. Writing things down is one of the most important innovations in human history. As well as being able to spread ideas accurately across distance and time, writing also provided the records needed for law to function.
In the United States, the average age for a girl to get her first period is 12. This does not mean that all girls start at the same age. A girl can start her period anytime between the ages of 8 and 15. Most of the time, the first period starts about 2 years after breasts first start to develop. If a girl has not had her first period by age 15, or if it has been more than 2 to 3 years since breast growth started, she should see a doctor.
The menstrual cycle is from Day 1 of bleeding to Day 1 of the next time of bleeding. Although the average cycle is 28 days, it is normal to have a cycle that is shorter or longer.Girls usually start having menstrual periods between the ages of 11 and 14. Women usually start to have fewer periods between ages 39 and 51.Women in their 40s and teens may have cycles that are longer or change a lot.he menstrual cycle is from Day 1 of bleeding to Day 1 of the next time of bleeding. Although the average cycle is 28 days, it is normal to have a cycle that is shorter or longer.