Menarche is the onset
of menstruation. Menarche is preceded by puberty-induced body changes that occur
between ages 9 and 16 years. The age at which menarche occurs is
affected by genetic and environmental factors. Menarche may be delayed
by poor nutrition, high levels of exercise (athletes or dancers), and
several medical conditions, such as diabetes mellitus, congenital
heart disease, and ulcerative colitis. Early menarche may occur with
other conditions, such as hypothyroidism, CNS tumors, and head trauma.
Girls usually show an increase in height of only 2 to 3 inches after
the onset of menstruation.
Effect of Menarche on Height, Weight, and BMI; Relation With
Obesity
Menarche is attained earlier by well-nourished adolescents. The
adolescents look clumsy at the first phase of their development as the
growth pattern is uneven including the lengthening of the calves and
forearm followed by the hips, chest, and shoulder. Presently, menarche
is preceded in girls about 8–9 years , boys attains height surge after
13 while a typical girl attains 95% of her adult height at about 1
year before menarche and the rest after attaining adolescence.
After the main growth spurt starts, it continues for 2–4 years at a
much slower rate in boys whereas girls growth outperforms. The
beginning of the increase in growth velocity is about age 11 in boys
and 9 in girls; but varies widely from individual to individual. Long
bones epiphysial closure is a remarkable end point of adolescent
growth. If the epiphysial closure is earlier as a consequence of
malnutrition, the full potential height fails to be achieved. On
average, smaller parents are having smaller children than children of
taller parents; bone age is fairly accurate with chronologic age,
those children usually show an appropriate rate of growth during early
years of life and childhood days and accomplish sexual maturation and
pubertal growth spurt at the usual ages.
The growth rate in menarche is associated with both the age and the
height during the year prior to the menarche. Postmenarche girls were
having a high BMI with significantly higher height and weight than the
premenarche counterparts. Growth rate changes before and after
menarche supported that the relationship between height and age is
statistically significant (0.05 and 0.01 level of significance),
demarcating their entrance into adolescence. The magnitude of the
growth slope changes before and after menarche is almost 0.3 cm per
year. In some previous studies menarche age was positively associated
with height and negatively associated with weight and BMI. The various
factors affecting the age at menarche directly and indirectly are
geographic, socioeconomic, and environmental factors.