At 16, if a girl hasn't had her period, what should she do?

Patient's question:

Age
Detailed medical condition and purpose of consultation: 16 years old, but menstruation has not yet arrived, wondering if it is normal

Doctor's answer:

Hello, the age of menarche for girls is approximately between 10 and 16 years old. The age of menarche varies, it can be as early as 11-12 years old, or as late as 16-18 years old. If menstruation does not occur after the age of 18, it is considered an abnormal phenomenon.
The timing of menarche is related to factors such as genetics, environment, nutrition, and economic conditions. In hot climates, menarche tends to occur earlier, while in cold climates, it tends to occur later. Girls in developed cities tend to experience menarche earlier, while those in remote mountainous areas tend to experience it later. Girls who are physically healthy and have good nutritional conditions tend to experience menarche earlier, while those who are weak and have poor living conditions tend to experience it later.