Menstruation Onset at Puberty

by Elizabeth
(U.S.A)

Menstruation, cyclic monthly bleeding, starts in teenage on attainment of puberty. Can I tell when my daughter will get her first menstrual period?

The Expert, Ren Chats, Answers:

Average age for the onset of menses is 12 years & 9 months to 13 years & 9 months. This is generally true for all ethnic groups and all geographical regions in the world.

The age at which first sign of initiation of puberty is noticed relates with the age at which the first period sets in.
Tiny breast buds are the first external sexual character noticed around 10 yrs of age. About 6 to 12 months later sparse growth of pubic hair is seen.

Interval between the first period and the appearance of breast buds is usually 24 to 30 mo, but can be as long as 6 years.

On the other hand, 8 - 10 percent of normal girls get their first period even before 11 years of age. Therefore, age at menarche can vary from 9 to 16 years.

Why so?

The age of menarche is closely related to successful sexual maturation. It coincides with stage 4 of sexual maturation rating for external sexual characters, also known as Tanner Staging .

As mentioned above, first period usually comes 30 months after the initiation of puberty; the range of variability being 12-36 months.

Even with perfect health, age of onset of puberty itself is very variable:

1. Depending on the inherited potential, each child goes through the stages of pubertal development at her own pace.

2. Late bloomers have delayed onset of puberty. This implies that the age of onset of menstruation is dependent on child’s biological maturation rather than her chronological age.

3. Hormonal changes associated with puberty: Increase in secretion of Gonadotropin releasing hormone, GnRH, by neural cells of hypothalamus triggers pubertal changes. It is also essential for the onset and continuation of normal monthly periods.

Gonadotropin releasing hormone is crucial for stimulation of pituitary hormones secretion and for functional maturation of the ovaries.

Factors that affect onset of menstruation:

1. Genetic: Usually the age of onset of menstrual cycle correlates with the age at which the mother and the grandmothers had their first period.

2. Nutrition: Essential nutrition is crucial for optimal growth during teenage. During pubertal growth spurt a girl gains 4-5 centimeters in height and 3-5 kilo in weight every year for 4–5 years. Corresponding bone structure and muscular mass formation accounts for almost half of that in an adult.

Changes in body shape often worries young girls, and some may even end up with eating disorders . Therefore, it is important to reassure teenage girls about the essential fat deposition and weight gain associated with puberty. Best is to maintain BMI percentile chart, which would clear all doubts on weight gain.

3. Percentage of body fat: 17 percent fat of total body weight is essential for onset of menstrual cycles; whereas minimum of 22 percent fat of total body weight is necessary to maintain normal ovulatory cycles.

Onset of periods can be delayed in girls who restrict their caloric intake and body weight.

4. Activity: Active lifestyle is an important prerequisite for proper functioning of hormonal network. Endorphins thus secreted create happy feelings, balanced psychosocial status, cause appetite modulation, and the release of sex hormones.

However, excessive indulgence in regular physical exercises, as in athletes, can delay the onset of menstruation.

Athletic amenorrhoea is well known to occur in athletes even after normal menarche at onset. This is believed to be due to depletion of body fat levels, and consequently affecting the sex hormones levels unfavorably.

The contrary is also true: Obese girls may experience early menarche, but then causes of obesity should be looked into, especially: Rule out polycystic ovarian disease.

5. Chronic ill health: A child suffering from chronic ill health can have delayed onset of monthly periods.

Have a look at how many hormones are at play during normal menstrual cycle, including
the body temperature variation one experiences click here