Used to be that seventh grade was the typical time for girls and, maybe a year later, boys to make the sometimes awkward transition of puberty. But more and more, studies show that young girls, especially, are showing signs of adolescence as early as third or fourth grade and that the average age of puberty is falling. What do these developments mean? Should parents be concerned? Virginia Commonwealth University professor Dr. Paul Kaplowitz, came on the “Today” show to discuss the issue. Here is an excerpt from his new book, “Early Puberty in Girls”:
What most parents understand about puberty is based on their own experience with it. Women typically recall the time of their first menstrual period (we use the term menarche when we refer to this event), and men often remember the grade they were in when they shot up four inches and kept outgrowing clothes and shoes. Some people remember puberty as a stressful time, though many of the stresses were likely more related to the difficult process of separating from one's parents and identifying with one's peers than to the hormonal changes themselves. Some mothers I have talked to who had puberty distinctly earlier than their peers recall feeling different or isolated, particularly if they went through menarche by age 10 and had no friends who had been through it before them. However, most parents I talk to do not have enough recollection of the timing and sequence of events their bodies went through between ages 10-12 and 15-17 for it to be of much help in deciding how worried to be or how to advise their children in the event one of them shows signs of puberty at an early age.To really understand what is or is not happening when a young child exhibits signs of puberty, a basic understanding of the physical and hormonal events of puberty is very helpful. In this chapter, I will describe these events in language that is as nontechnical as possible, while setting the stage for the discussion of the mechanisms underlying early puberty in the chapters that follow. I will start with a discussion of normal puberty in girls, followed by a shorter discussion of normal puberty in boys.
The Normal Physical Changes of Puberty in GirlsBreastsIn order to be sure that a girl has started to undergo puberty, there needs to be breast tissue. This sounds simple and quite obvious, but as I will explain later, it is remarkable how often this fact is ignored. In girls who have not started puberty, one can often detect a tiny amount of tissue under the nipple, the breast bud, which is usually no larger than 1/4 inch in diameter. It is only when estrogen production starts to increase that the breast bud starts to increase in size. One can also see a thickening and darkening of the skin overlying the breast tissue, called the areola, and often a protrusion of the nipple at the center of the areola. Pediatricians rate breast development using the Tanner scale, developed by Dr. James Tanner. The five stages are defined as follows:Stage 1: Prepubertal; no breast tissue presentStage 2: Breast bud stage: a small mound of breast tissue under the nipple, slight enlargement of the areolaStage 3: Further enlargement of the breast and areola but no separation of their contoursStage 4: Areola and nipple form a separate mound above the level of the breastStage 5: Fully mature adult breast, with only the nipple projecting above the level of the breastWhen puberty is in full swing, the amount of time needed to progress from stage 2 to stage 5 is between two and three years. However, with early-maturing girls, the progression is often slower, and as I will point out in the next chapter, very young girls can have stage 2 breast development and not progress at all for many years.In slender or non-obese girls, simple inspection is usually adequate for a parent or a pediatrician to tell if a girl has breast development. However, in overweight girls, this is often difficult, since in the sitting position, fat over the chest can look very much like breast tissue. One clue is that when the girl lies on her back, the fat redistributes itself over a wider area and what looks like breast tissue largely disappears. The most reliable method, however, is simply palpating, or feeling for breast tissue with one's fingers. Breast tissue feels firmer and rounder than fat tissue and is located directly under the areola. My general rule is that if the diameter of the breast tissue held gently between the thumb and index finger is over 1/2 inch, it is likely that the breasts are starting to enlarge. However, it often takes a few months of observation to be sure.Pubic and Underarm (Axillary) HairThe greatest source of confusion among both parents and primary-care physicians is the meaning of the appearance of pubic hair in a young child. We are talking here about not the fine, light-colored hair similar to what may exist on other parts of the body, but dark and (if it is long enough) curly hair on both sides of the opening of the vagina and eventually above the vagina (an area called the pubic symphysis). We also use the Tanner scale for describing the extent of pubic hair growth as follows:Stage 1: No pubic hairStage 2: Sparse growth of long, dark hairs, straight or slightly curled, along the sides of the opening of the vaginaStage 3: Hair is darker and curlier and now spreads thinly over the pubic symphysisStage 4: Hair is thicker and looks like what one would see in an adult, but covers a much smaller areaStage 5: Hair is adult in quantity and type, distributed like an upside-down triangleIt is important to understand that growth of pubic hair has nothing to do with estrogens made by the ovaries. It is due to male-type hormones made in the adrenal glands, which we refer to as adrenal androgens. The adrenal glands are small but vital glands that sit just above the kidneys; they also make cortisone (a hormone that is essential to life) and a salt-retaining hormone.Because in many children pubic hair appears at the same time as other signs of puberty, there is a widespread belief that pubic hair equals puberty. The truth is that pubic hair can appear several years before other signs of puberty (e.g., breasts) or can appear at a later time. Axillary hair is thought to reflect the same hormone changes that cause pubic hair, though in most girls detectable axillary hair will appear three to six months after pubic hair.What regulates the ability of the adrenal glands to increase androgen production is still not clear, but we know that the hormones that stimulate the ovaries to make estrogens are not involved. In the past, most girls were said to develop pubic hair between ages 8 and 12, but more recently its appearance between ages 5 and 8 has become increasingly common.Body Odor
Another sign thought to be characteristic of puberty is development of an adult-type body odor, originating entirely in the underarm area, or what physicians call the axilla. Although this phenomenon as it occurs in children has received little scientific attention, I have concluded after years of talking to parents that the development of body odor, like pubic hair, is closely related to the increase in adrenal androgen secretion. This is because the timing of the onset of body odor is usually close to the time of appearance of pubic hair. Sometimes parents report detecting the odor three to six months before any pubic hair is evident. How adrenal androgens might influence the nature of what comes out of our axillary sweat glands is not clear, nor is it clear what the role of axillary odor in human reproduction might be. It may have evolved as a way for humans to recognize when another member of the species is close to reproductive maturity.Pubertal Growth SpurtOne of the most dramatic changes occurring during puberty is the rapid growth that typically becomes apparent within a year after the appearance of breast tissue and is directly related to increased estrogen and growth hormone production. Prior to puberty, the normal rate of growth is about 2 inches per year, but this increases to about 4 inches per year during the most rapid phase of the pubertal growth spurt. In many girls, this occurs sometime between ages 10 and 12, but there is a great deal of variability. Men may recall that when they were in fifth or sixth grade, the girls shot past them in height, only to be passed two to three years later, when the guys finally had their growth spurt.One occasional source of confusion is when we see what looks like a growth spurt in children who are very overweight, since overweight kids often grow more rapidly than normal. However, if the breasts are not enlarging, this is not a true pubertal growth spurt.MenarcheFor years, the average age at which white girls have their first menstrual period has been about 12.7 years, though a recent study based on data collected between 1988 and 1994 suggests that this has decreased slightly to 12.5 years. In black girls, the average age of menarche is 0.4 to 0.5 years earlier, or a little over 12 years. Again, there is a great deal of variability from child to child, with some normal girls starting their periods as early as age 10 and others not starting until 15. Genetic factors are important, in that mothers who started their periods early are more likely to have daughters who start early. Another important factor is body weight and fat content. Numerous studies have shown that overweight girls have menarche earlier and thin girls, especially thin, athletic girls (particularly gymnasts, competitive swimmers, and ballet dancers), start later. In the landmark study of Marshall and Tanner, 192 white British girls were examined several times as they progressed through puberty. Published in 1969, the study showed that the average time it takes to progress from Tanner stage 2 breast development to menarche (which typically occurs at Tanner stage 4) was 2.3 years. However, there is reason to believe that more recently the interval has gotten longer. One study from Spain showed that the interval from the start of breast development to menarche averaged 2.9 years in early-maturing girls but only 1.5 years in late-maturing girls. Although reliable data has not been published recently in the United States, it is reasonable to assume that with girls who mature earlier, the average interval between appearance of breasts and menarche may be closer to 3 years than to 2.3 years.The onset of menses also signals that the pubertal growth spurt has nearly been completed. Most girls grow only 1 to 4 inches after their first period, with early-maturing girls having more growth left at menarche than late-maturing girls.
Excerpted from "Early Puberty in Girls" by Paul Kaplowitz Copyright ©2004 by Paul Kaplowitz. Excerpted by permission of Ballantine Books, a division of . All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.