Puberty describes the normal biological changes in the body that lead to sexual maturity, the ability to produce children. Normal puberty begins between ages 8 and 12 years in girls and between 9 and 14 years in boys. Precocious puberty means that the biologic changes begin much earlier than expected. The timing and sequence of puberty are controlled by hormones. Children who have Spina Bifida with hydrocephalus—especially girls—are more likely to have precocious puberty than other children.

Humans have a biological clock in the brain that triggers the production of hormones at the appropriate age. One of these is called gonadotropin-releasing hormone (GnRH). GnRH is made in the hypothalamus and causes the pituitary gland to release hormones called gonadotropins. These hormones, in turn, flow through the blood stream and stimulate the ovaries in girls and testes in boys to make sex hormones. The sex hormones, especially estrogen in girls and testosterone in boys, cause sexual maturation.

The physical changes seen in puberty have been classified using a system called Tanner staging, where stage 1 is child-like (before puberty) and stage 5 is full maturity. In girls the usual sequence includes (1) start of breast development, (2) rapid increase in height and widening of the hips, (3) pubic hair, which appears three to six months after breast development, (4) axillary hair (hair under the arms), and (5) menstruation, which starts two to two-and-one-half years after breast development is noticed. A change in body odor may also appear early in this sequence.

The average age for the start of breast development in girls is nine to 10 years. African-American girls have earlier onset of puberty than do Caucasian girls. In one study, for example, African-American girls started breast development 12 months before Caucasian girls did. Breasts typically take three or more years to go from Tanner 2 to Tanner 5. As with all biologic events, a range of normal occurs. However, if significant breast development begins before age eight years, it is considered precocious. (Occasionally girls will have some development of the breast, called thelarche, with no other signs of puberty. This isolated change is usually considered normal.)

In males, the usual sequence includes:

1. increase in the size of the testicles
2. growth spurt
3. increase in size of the penis
4. pubic hair
5. axillary hair

The second major problem with precocious puberty is that bodily changes happen much earlier than in other children of the same age, which makes the children appear different. As a result, children with precocious puberty may be teased about their sexual development; such teasing is especially common with girls who develop breasts. Or girls may be subject to sexual advances for which they are not psychologically ready. Boys may become more aggressive than their peers. In general, children with precocious puberty may feel isolated and rejected socially. Teachers and other adults may expect these children to act older than their ages. This, in turn, may frustrate the children because they cannot live up to expectations. The isolation and unrealistic expectations, which are common in children with Spina Bifida without precocious puberty, make functioning even more difficult.

Although it is not certain why children with Spina Bifida and hydrocephalus are more likely to have precocious puberty, most people believe that the hydrocephalus interferes with the biological clock. If your child has precocious puberty (before age eight in girls and before age nine in boys), or has an unusual sequence or too rapid sexual development, he or she should be evaluated by a physician or nurse clinician who is knowledgeable about these issues. Usually, a referral to an endocrinologist (a person who specializes in hormones) is made. If no other problems are found, the most commonly used treatment to delay the onset of puberty is to begin injections of a medicine that interferes with the hormonal system.

The most commonly used medicine is called leuprolide (Lupron). This medication, which is injected into muscles once a month, has a chemical structure similar to GnRH and fools the body (probably by making the pituitary gland less sensitive to the real hormone). It usually stops the progress of puberty after three to six months, and may reverse some of the changes that had already occurred. It usually is given for several years. Most people believe that treatment also allows individuals to be taller than they would have been without using the medication. Most importantly, the delay caused by the treatment should allow the children/teens (and parents) to adjust to their sexually maturing bodies and feelings, and help them develop a healthy sexual identity.

This information does not constitute medical advice for any individual. As specific cases may vary from the general information presented here, SBA advises readers to consult a qualified medical or other professional on an individual basis.