Puberty in Girls

Puberty is the period of growth and development in which children and adolescents develop adult physical features, such as breasts or pubic hair, and become able to reproduce (have babies). For girls, puberty usually begins at age 8½ to 10 years and lasts about 4 years.

When puberty starts in a girl depends on the following:

• Weight: Girls who are overweight usually start puberty earlier

• Nutrition: Girls who don't have access to or can't absorb proper nutrition start puberty later

• Genetics: Daughters of mothers who started puberty early are likely to also start early

The entire reproductive system, including puberty, is controlled by hormones. Hormones are chemical messengers made in certain parts of your body that travel through the blood to signal other parts of the body what to do.

Puberty in girls starts when hormones released by the brain cause the ovaries to develop. The ovaries then release the hormone estrogen. Estrogen causes development of the girl's reproductive system, including her:

• Breasts

• Vagina

• Ovaries (the pair of organs where eggs are made and stored)

• Uterus (the organ where a fetus grows before being born)

Menstrual periods usually begin a few years after puberty starts.

The following physical changes take place, usually in this order:

• First, breast growth—this usually happens between ages 8 and 13

• Shortly after, hair starts to grow in the armpits and genital area

• A growth spurt in height happens—growth usually slows down when periods start

• Periods (menstruation) start about 2 to 3 years after the start of breast growth

• Girls usually stop growing in height between ages 14 and 16

The first period usually happens about age 13 though it can be anytime between ages 10 and 16. Periods may not come regularly at first. It can take up to 5 years for the menstrual cycle to become regular. As girls grow, their body shape will change. Their hips and thighs get bigger, and they get more body fat. This is a normal part of puberty in girls.

Milestones in Sexual Development

During puberty, sexual development occurs in a set sequence. However, when the changes begin and how quickly they occur vary from person to person. For girls, puberty begins at age 8 1/2 to 10 years and lasts about 4 years. The chart shows a typical sequence and normal range of development for the milestones of sexual development.

Problems with puberty usually involve hormones. There are many different hormone problems that result in too few hormones so that:

• Puberty is delayed or doesn't start at all

Less often, there are too many hormones and the girl has:

• Early puberty