Puberty is the process of physical changes by which a child’s body becomes an adult body capable of reproduction.1 For females, puberty is marked by the onset of menstruation, an important milestone in their reproductive lives.
What Is the Menstrual Cycle? Menstruation is when the body sheds the lining of the uterus (womb). Having regular menstrual cycles is a sign that reproductive parts of the body are working normally.2
Two of the most significant differences between puberty in girls and boys are the age which puberty begins and the major sex steroids involved. Girls attain reproductive maturity about 4 years after the first physical changes of puberty appear. In contrast, boys accelerate more slowly but continue to grow for about 6 years after the first visible pubertal changes.3 Any increase in height beyond the post-pubertal age is uncommon for both boys and girls.
In North America, the first sign of puberty for young girls—breasts budding—normally occurs between ages 8 and 13, with an average age of 10 years.4
The average duration of puberty is 4 years but can range from 1.5 to 8 years.4
The first menstrual period for U.S. girls today occurs on average between ages 12 and 13, compared with age 14 for girls in 1900. Regular ovulation is established by about 20 menstrual cycles after the first period.4
A normal menstrual cycle lasts about 28 days but can vary from 21 to 45 days in adolescents.4
In developing countries, abnormal uterine bleeding appears to affect about 5–15% of women of reproductive age.5
Abnormal uterine bleeding is a leading indication for hysterectomy, the most common non-obstetric operation in women in both the United States and the United Kingdom.5