Most girls get their first period between the age of 9 and 16, and puberty normally begins around the age of 8 to 14. Most girls will not start menstruation until they weigh at least 100 pounds. Puberty hormones lead to girls developing breast, hips, pubic hair, and growing in height.
According to Frisch, a minimum level of fatness (17% of body weight) is associated with menarche; however, a heavier minimum weight for height, representing an increased amount of body fat (22%), appears necessary for the onset and maintenance of regular menstrual cycles in girls over 16 years of age.
Being overweight or obese
The excess oestrogen can affect how often you have periods, and can also cause your periods to stop. Your GP may refer you to a dietitian if you have a BMI of 30 or more, and it's affecting your periods.
Another common cause of delayed puberty in girls is lack of body fat. Being too thin can disrupt the normal process of puberty. This can occur in girls who: Are very active in sports, such as swimmers, runners, or dancers.
Girls who are underweight or who have eating disorders may notice a delay in the start of their periods. Girls who are very athletic might not get their periods until they stop exercising or competing so vigorously. Severe stress or some illnesses also can delay menstruation.
Excessively low body weight — about 10% under normal weight — interrupts many hormonal functions in the body, potentially halting ovulation. Women who have an eating disorder, such as anorexia or bulimia, often stop having periods because of these abnormal hormonal changes.
Your periods will start when your body is ready. This is usually between age 8 and 17, or 2 years after your first signs of puberty. Possible reasons for delayed periods include being underweight, doing lots of exercise (including dance, gymnastics and athletics), stress and a hormone imbalance.
Amenorrhea has many causes, including hormone problems, eating habits and exercise, or a birth defect. Your teen may need blood tests and a pelvic ultrasound. Treatment may be done with hormones or other medicines, changes in diet or exercise, and calcium supplements.
Being underweight (per the BMI chart) isn't required in order to lose a period. Recent weight loss can have a similar impact to being underweight, regardless of starting weight.
Typically, a girl gets her period about 2 years after her breasts start to develop. Another sign is vaginal discharge fluid (sort of like mucus) that a girl might see or feel on her underwear. This discharge usually begins about 6 months to a year before a girl gets her first period.
If you feel heavy and bloated during your period, it's not in your head. “Water retention is a common premenstrual symptom and weight gain during your period is normal,” says Nita Landry, M.D., a board-certified OB/GYN and the author of Dr. Nita's Crash Course for Women. “Every person is different.
Usually if periods never start, girls do not go through puberty, and thus secondary sexual characteristics, such as breasts and pubic hair, do not develop normally. If women have been having menstrual periods, which then stop, they may have secondary amenorrhea. Secondary amenorrhea is much more common than primary.
Changes to hormone levels
Previous studies reported that girls with obesity start puberty and experience their first menstrual period earlier than girls with normal weight.
Puberty in women normally occurs between 11 and 14 years of age. If a girl reaches a particular weight (around 100 lb (45 kg)), the onset of puberty is triggered. The heavier the child, the earlier puberty occurs, possibly affecting risk of later disease.
If your daughter hasn't had her first menstrual cycle by 15, or if more than three years have passed since she started developing breasts, she should see a physician.
Sometimes, irregular periods can be caused by some medicines, exercising too much, having a very low or high body weight, or not eating enough calories. Hormone imbalances can also cause irregular periods. For example, thyroid hormone levels that are too low or too high can cause problems with periods.
Girls usually get their first menstrual period when they're 12 or 13. It's a sign that your body is maturing, so that one day, if you want to, you should be able to have a baby. By age 15, 98% of teens have started their periods. If you're not one of them, make an appointment to talk to your doctor.
Pubic hair – Once her pubic hair starts growing, you can expect her period to develop in one to two years. It may begin soft and thin but it will become courser and thicker towards the end of puberty.
Menarche is defined as the first menstrual period in a female adolescent. Menarche typically occurs between the ages of 10 and 16, with the average age of onset being 12.4 years.
“This is a big deal for me,” she said. And the Victoria's Secret model added that losing your period is incredibly common among models — a standard she wants to change.