This is the period during which adolescents reach sexual maturity and become capable of reproduction. It is a complex series of physical transition through which a child’s body matures into an adult form capable of sexual reproduction. On the average girls attain puberty at 10 – 11 years and boys around 11-12 years. Girls also tend to complete puberty around ages 15-17 years. In general, a critical body weight seems to be the most salient issue in the development and maintenance of puberty. In the 21st century, the average age at which children reach puberty is lower compared to the 19th century when it was about 15 years for girls and 16 years for boys.
The most visible changes during puberty are growth in stature and secondary sexual characteristics.
The physical changes that occur during puberty in girls are breast development; pubic and axillary hair; Growth spurt; Onset of menstruation which occurs approximately 2-2.5 years after the onset of puberty. In males it includes increased size of the testes in addition to the growth spurt and hair growth, development of pimples, increased muscle mass; ‘wet dreams’.
Two main physiological events in puberty are
Physiology of puberty
During childhood levels of reproductive hormones are very low. However from the age of 8-9 yrs, hormone , Gonadotrophin releasing hormone (GnRH)is secreted in pulsation of increasing amplitude and frequency. These secretions are initially sleep related but as puberty progresses, these extend throughout the day. This stimulates FSH and LH from the brain and subsequently oestrogen secretion from the ovaries which initiates the physical changes of puberty including breast development and growth of the skeleton leading to pubertal growth acceleration. The ovarian hormone, estradiol also induces maturation of the skeleton eventually resulting in fusion of the growth plates and cessation of linear growth.
In boys LH stimulates some special cells in the testes called leydig cells to produce testosterone.
Increased testosterone stimulates growth of certain tissues within the testes leading to an increase in testicular volume. FSH also stimulates further growth of semniferous tubules and testicular volume. Testosterone is also responsible for most of the changes that occur in boys during puberty. Some of the testosterone might be converted into the female hormone estradiol and thus can be responsible for the mild increase in breast size seen in some boys. When a boy attains puberty, erections are more common especially during sleep and most wake up with an erection which is perfectly normal. It can however be embarrassing when it occurs spontaneously in the daytime.
The timing of the growth spurt varies by gender occurring approximately two years earlier in girls than boys. The limbs (arms and legs) accelerate before the body with the lower portions of the limbs accelerating before the upper portion.
In later puberty however the growth spurt is primarily truncal. Because boys achieve growth spurt later than girls they have a further two years of prepubertal growth before the growth spurt. Growth spurt last approximately two years in both sexes.
There are phrases that are used to describe a deviation from the norm.
These include: Precocious puberty which is the onset of puberty at an age 2-3 standard deviation below the mean age of onset of puberty.
It includes the appearance of breast before the age of 8years in girls and testicular enlargement before the age of 9years in boys.
It is classified as central precocious puberty and peripherial precocious puberty. Central puberty is when the cause can be traced to the hypothalamus or pituitary. Peripherial precocious puberty occurs when secondary sexual development is induced by sex steroids from other abnormal sources.
Delayed puberty: Doctors start to evaluate boys who have no signs of puberty by age 14years and girls who have no signs of puberty by age 12-13 years or who have not menstruated by age 15 to 16years.
Problems associated with puberty include: Anaemia-the shortage of blood which occurs more in girls due to blood loss during menses. Gynecomastia- is another problem seen in some boys, it is the excessive enlargement of the breast. Psycosocial correlates of puberty (especially precocious puberty) because of the physical appearances of the individuals. For example girls who mature much earlier than their peers might find themselves adding more weight in certain areas and generally appear larger in size than their peers. This can lead to a negative body image of themselves and ultimately lower self esteem. Dysfunctional uterine bleeding, seen in girls. The menses are irregular in nature. This is because the first three years or so of menses are not preceeded by ovulation which is needed to “time” the menstrual cycle. Unintended pregnancy can also result
In conclusion, puberty is a natural period which every child is expected to experience. Guidance from knowledgeable parents is key to negotiating this period successfully.