Your First Period – Menarche

Your first period is called menarche. It happens after a lot of changes in your body. The most important changes that drive your first period are the following:

• Your weight increases and you get more body fat, typically around 17% body fat
• A special part of your brain (the hypothalmus) begins to function causing your hormone the cycle to start
• Your ovaries begin to make estrogen because of the pituitary hormones
• This estrogen causes your growth spurt, widening of your pe;vis to form hips, breast growth and the formation of regional adipose tissue.. After about 2 or 3 years of this, the estrogen will also cause your uterus to grow and mature
• Estrogen also stimulates growth and vascularity of the the lining of the uterus (endometrium).
• The fluctuations of your hormone levels results im more or less blood flowing to parts of the endometrium
• When the blood supply dries up, some of the endometrium tissue dies. This dead tissue will tear lose and together with some blood, will form your menstrual flow through your cervix and vagina and out of your body

Your menstrual flow consists of a combination of fresh and clotted blood with tissue from your endometrium. Your first period flow is often brighter than your following periods. The amount can be very small and very short. It may even be just a single spot of blood. You may or may not experience abdominal cramping or other period signs.

Menarche does not neccisarily mean that a girl is fertile an can conceive. During the first year after menarche, a girl typically do not ovulate for 80% of her cycles. During her third year, she ovulates about halve of her cycles/. By year 6, she ovulates about 90% of her cycles

Most women will only start to ovulate every cycle in their early twenties. By that time, her cycles should be predictable and there should be consistent intervals between periods, the length of her period should be predictable and consistent, and the flow should be predictable and consistent patterns of flow (e.g., heaviness or cramping).

Continuing ovulation typically requires a body fat content of at least 22%.

WARNING: Not every girl follows this pattern. Although it is very unlikely, a girl can ovulate before her first period, and become pregnant from unprotected intercourse.

Age

Women have been starting menarche earlier and earlier. It is thought that good medical care, high calory diets, and hormones found in the environment iscausing this. It is not surprising to find girls in puberty at age 8, 9 or 10 today.