Behavior & Development • Jan 11, 2016

When should kids start puberty?

Sad but true– when 8-year-olds have signs of puberty it’s usually normal. Nevertheless, it’s unnerving to find pubic hair on your 4th grader or buy a bra for your daughter who still wears a Brownie uniform. Occasionally, early puberty can be a sign of serious illness, especially if it starts before 8 years of age in girls or before 9 years in boys. So when do parents need to be alarmed and take their child to the doctor? Here are some guidelines from the American Academy of Pediatrics Clinical Report on Evaluation and Referral of Children With Signs of Early Puberty.

When to worry about early puberty

puberty table

When should kids get armpit hair and pubic hair?
Pubic hair and underarm/armpit hair (medically known as axillary hair) appears when the adrenal glands increase production of a hormone called DHEA. This hormone also causes body odor and sometimes mild acne. This part of puberty is called adrenarche. Adrenarche is usually normal in girls who are at least 8 years old, and boys who are at least 9 years old.  Even when pubic and underarm hair appear in children younger than this, it is still usually nothing to worry about, but your child does need to see their pediatrician for an exam. The doctor will plot your child’s rate of growth on a growth curve and do a genital exam. Early pubic and armpit hair is considered normal if a child is growing normally and tracking along the same percentile on the doctor’s growth curve, and there is no significant enlargement of the clitoris in females or penile growth or testicular enlargement in boys.

When should girls start to develop breasts?
Most girls start breast development around age 11, but about 15% of African American girls and 5% of caucasian girls will start breast development before age 8. Girls who start breast development before age 8 should be seen by their pediatrician to be sure there is not a serious endocrine disorder causing the early puberty, but most of the time it is normal. Girls who are 14 years old and have no breast development should be evaluated for late puberty. Breast development starts with breast buds, which are round areas of firm tissue under the nipple. The medical term for the beginning of breast development is thelarche. It is normal and common for girls to have uneven breast development, with one breast developing faster than the other. Some girls will develop the appearance of breast tissue, but not have any firm breast buds. This is called lipomastia, and it is really just a collection of fat in the breast area. Lipomastia does not represent puberty.

The most common form of early breast development actually occurs in toddler girls under 2 years of age. These young girls can develop breast buds that can change in size and even disappear altogether. Most of the time, this very early breast development in toddler girls is not serious. The medical term is premature thelarche. It is unclear what causes premature thelarche, but one theory is that ovarian cysts may be releasing hormones that stimulate the breast bud development.

When should girls get their period?
Girls usually start their period about 2 years after breast buds appear. The average age of first menstrual period, or menarche, is about 12.5 years in the United States. There are significant racial differences in age of first menstrual period, with non-hispanic African American girls starting earlier than girls of caucasian and Mexican descent.

When should a boy’s penis and testicles grow during puberty?
Testicular and penile growth are usually the first signs of puberty in males, although occasionally pubic and underarm hair can appear first. Most boys start puberty between age 12-16, but puberty is not considered early in a boy unless he is under 9 years of age.

How has the age of onset of puberty in the United States changed over time?
Age of onset of puberty has not changed much in the United States over the past 50 years.

What causes early puberty?
Early puberty is usually normal, but can also be caused by exposures to medications and chemicals, including estrogen and testosterone creams and gels, essential oils such as tea tree oil and lavender oil, and possibly a group of toxins found in some plastic products called phthalates. If a parent or other family member is using hormonal creams or gels, be very cautious about washing hands after using them and before touching household surfaces.

Is your child smelly and sweaty?  Here are some tricks to keep them smelling sweet.  

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