Puberty in girls

This is  a good article on puberty development in girls. Important points are highlighted in bold.

Normal puberty in girls is a complicated topic. To understand what is normal, we need to start with some basic information. Before any visible changes take place, hormonal changes are occurring for a couple of years. These hormonal changes start in the adrenal glands, two small organs that rest on top of either kidney. These hormones send signals to an area of the brain known as the hypothalamus and the pituitary gland. The hypothalamus and the pituitary, in turn, send hormonal signals to the gonads, which in the case of girls, are the ovaries. This system of signaling takes a couple of years to become fully established, but once it does, then the physical, visible changes that we call puberty begin to take place.


Puberty follows a fairly consistent sequence in girls. Doctors stage the physical changes on a scale of 1 to 5, called Tanner staging. Children who do not show any physical changes of puberty are at Tanner stage 1. Adults who have completed puberty are at Tanner stage 5. For girls, Tanner staging is done to assess both breast and pubic hair changes. Sometimes the changes in these two areas are not at the same Tanner stage at the same time, and that is okay.


The first visible changes are usually the development of breast buds (known as thelarche). This usually occurs between ages 7 to 13 and marks the transition to Tanner stage 2. Again ethnicity plays a factor in the age at which puberty first appears. Up to 15% of African-American girls with have breast buds by age seven years. Percent body fat is another factor associated with the earlier onset of pubertal changes. However, many overweight girls only appear to have breast development because of increased body fat deposited on the chest. This “pseudo” breast development can usually differentiated from real breast development by a doctor during the physical exam. Breast budding may begin on one side before the other and is often accompanied by tenderness. The tenderness generally goes away in a few months.


Following breast development, most girls then have the development of coarse, dark pubic hair (adrenarche) generally limited to the labia majora. This is also Tanner stage 2. Some girls (about 15%) will have the development of pubic hair before breast development. The amount of pubic hair increases to an almost adult amount prior to the onset of the menses (Tanner stage 3).


The onset of the menstrual cycles (menarche) begins about 2 to 2 1/2 years after the onset of breast development. Thus, the menstrual cycle can occur anywhere from age 9 to age 15 and be considered 'normal.' Most girls do not have regular, predictable menstrual cycles for another year or two.
Most girls have their growth spurt in the year preceding the onset of the menstrual cycles and have reached closed to their final adult height, unlike boys who have their 'growth spurt' later in puberty. Most girls stop having bone growth within 18 to 24 months after the onset of menses.

Source: http://www.keepkidshealthy.com/development/puberty_girls.html