How Girls Are Developing Earlier In An Age Of 'New Puberty'

December 2, 2014

Guests: Louise Greenspan & Julianna Deardorff

TERRY GROSS, HOST: This is FRESH AIR. I'm Terry Gross. Here's a dilemma facing parents and teachers - many girls are going through puberty at an early age, developing breasts earlier than girls of previous generations, but that doesn't mean they're maturing emotionally and intellectually at the same pace. Here's some of the related questions my guests are investigating - what percentage of girls are going through puberty early? What environmental, biological and socioeconomic factors influence when puberty begins? And does early puberty correlate with an increased risk of breast cancer?

Doctors Louise Greenspan and Julianna Deardorff are the authors of the new book "The New Puberty." They're co-investigators in a long-term study of puberty. They've been following 444 girls from the San Francisco Bay Area since 2005 when the girls were 6 to 8 years old. The study is funded by the National Cancer Institute and the National Institute of Environmental Health Sciences. Dr. Deardorff is a clinical psychologist and is on the faculty of the University of California Berkeley School of Public Health. Dr. Greenspan is a clinical pediatric endocrinologist and is on the faculty UC San Francisco.

Dr. Greenspan, Dr. Deardorff, welcome to FRESH AIR. Let's start with, what are we talking about? What percentage of girls are going through early puberty, and how does that compare with the past?

LOUISE GREENSPAN: Well, the evidence suggests that in the past, age 8 was the cutoff for normal puberty. So we thought that less than 5 percent of girls were going through puberty before the age of 8. And I do want to make sure I define what we mean in the medical profession by starting puberty. A lot of the people in the lay public think that that means getting your period. And what we're talking about is actually starting with breast development and pubic hair. And what the research that we did with our colleagues found was that at age 7, 15 percent of girls had breast development, and at age 8, 27 percent had breast development. And in terms of pubic hair development, at age 7, 10 percent of girls had it, and by age 8, 19 percent had pubic hair development. So that was significantly higher than what had been found in the past.

GROSS: You're also seeing patterns in racial and ethnic variations.

GREENSPAN: Yes, we are. So if I'm going to pick on breast development as an example, at age 7, 25 percent of black girls have breast development compared to 15 percent of Hispanic girls and only 10 percent of white girls and 2 percent of Asian girls. And the same pattern can be seen for pubic hair development. So it seems that African-American girls are going through puberty much earlier, followed by Hispanic girls, and Asian and white girls are less affected and seem to be going through puberty later.

GROSS: Are you disturbed by the percentage of girls who are going through puberty at such a seemingly early stage, you know, earlier than in the past? To me, it sounds kind of upsetting because let's face it, a 7-year-old doesn't need to be going through puberty. They don't need to be - you know, to be growing into their sexuality at age 7.

GREENSPAN: So I think we do want to make sure we separate puberty and sexuality. For these kids, they're used to their bodies changing. They're losing teeth. They have to get new shoes every six months because their feet are growing. So for them, if the adults in their lives don't put it into a sexual context, it's just sort of part of a different change that can be happening in their body. So we have to be careful to immediately leap to sexualizing 7-year-old girls. And in addition, at the beginning these early changes are not things that anyone can see when the kids are clothed. And in fact, even the first pubic hair, some parents might not notice it because it's - of where it's located.

So the later stages is what becomes more apparent socially. And I think in terms of answering your question about whether I'm disturbed, there's the clinical person in me and the mother in me. And the clinician in me finds that my clinical work is now much more challenging because I can't tell the percent of kids who are part of this phenomenon compared to the kids that have a true hormone problem because we used to use age 8 as the cutoff for that and now we can't. The mother in me - I have a second-grader and a fourth-grader - and I'm looking at their peers, and I realize that now as a mom, I see this phenomenon. And a lot of these kids are not prepared for what's going to happen later.

JULIANNA DEARDORFF: Yeah, and - this is Julianna - and what I find concerning is that puberty is a process that's very sensitive to the environment. And we can move the timing of puberty unintentionally vis-a-vis environmental exposures. And so sometimes we think about, you know, puberty in and of itself and starting early has a lot of disconcerting aspects which we can talk about. But I also am concerned just, is this kind of a canary in a coal mine or a barometer for other things we're all being exposed to in our environments that may not be healthy for other reasons we're just not seeing those as obviously?

GROSS: Well, let's gets to some of that. You're concerned that there might be chemicals that we're exposed to on a regular basis that are contributing to early puberty. What are some of those chemicals?

DEARDORFF: You know, there are a number of chemicals that we talk about in the book, too long to list. But they're referred to as endocrine disrupting chemicals or EDCs. And also another term for that is hormone mimickers, and that's because in the body they mimic hormones. And in this case when we're talking about girls' early puberty, estrogen is the hormone that we're most concerned about.

GREENSPAN: And there's several chemicals that may mimic estrogen in the body. So in animal studies a big one that we're looking at, the culprit is called Bisphenol A or BPA. BPA was actually invented as a medical estrogen; it's a weak estrogen. And it ended up becoming ubiquitous in plastics. The concern is that it may leach out of these - it's also on paper receipts and in other compounds - the concern is that it may leach out of those and into our bodies and may act like an estrogen. And our study has not yet demonstrated that this one single chemical is causing early puberty, but it is one of the ones we're looking at.

And one of the problems with deciding which chemical is that there's no one single smoking gun. We live in a sort of toxic milieu of many, many, many chemicals, and it's actually becoming impossible to isolate a single one, so we're looking at the ones that may work together. Maybe they work one plus one equals three in terms of the additive effects.

BPA is one of the ones. We're also looking at flame retardants, we're looking at the organic phosphate pesticides as well, we're even looking at triclosan, which until recently has been ubiquitous in soap and toothpastes, and that may also be an estrogen mimicker. And it's an antibacterial agent.

DEARDORFF: Well, one of the reasons we were really motivated to get this book out there was so that folks could have some guidelines about how to use what many people call the precautionary principle, which is if you're not sure about it, find a safer alternative because the science just isn't there yet. Even though we know in animal studies many of these chemicals act as endocrine disrupting chemicals, we don't know a lot about how these chemicals act in humans, nor do we know much at all about how they act in children, which is where Louise and I really focus our work.

GROSS: So if the chemicals that you're talking about are contributing - like, let's say they are contributing, we don't know for sure - but let's say that they are contributing to early puberty by mimicking estrogen, that's what they're doing in girls. What is exposure to these chemicals doing to boys?

GREENSPAN: That's a really interesting question. And the jury is still out on what's happening with boys' puberty. There is some evidence that boys' puberty may be starting earlier as well, but we don't have the definitive studies that demonstrate that yet. One of the concerns is that the hormones that are estrogen mimickers might actually delay boys' puberty because boys' puberty is not an estrogen-related process. It's more of an androgen- or hormones like testosterone-related process. So the same chemical may have different effects in boys versus girls in terms of their pubertal development.

GROSS: And, you know, you and other people have speculated that the food we're eating - the food children are eating - you know, might be causing early-onset puberty. And a lot of people have suspected - oh, it's the growth hormones that are given to, like, chickens and cows that make our, you know, contribute to our dairy products and to the meat that we eat. But you say, no, it's probably not the growth hormones. It's probably the antibiotics that are fed to the chickens and cows. Why isn't it the growth hormones, and why do you suspect that it's the antibiotics?

GREENSPAN: The theory is that the growth hormones are digested in the intestinal systems so they have less of an effect biologically in the humans when we eat them. Growth hormone as a medicine, for example, is injected through the skin because it is broken down in the stomach.

The concern about antibiotics is that one of the reasons antibiotics are used in the food supply is not just to treat animals' infections. It's actually because when animals are given antibiotics, they get fatter and they go through pubertal development earlier. So it speeds up the process of raising a young animal to an animal that's ready for slaughter. And it makes them bigger so they're - it's more efficient. So the concern is if antibiotics are doing this to animals and that's actually why they're used in animals and they're not broken down in the intestinal system - in fact, they're absorbed orally in the stomach when we eat them - could they be having a similar effect in kids? And that's the concern.

GROSS: And is there evidence that it has that effect, or is it just speculation at this point?

DEARDORFF: You know what? It's just speculation. These are theories that are out there. But there hasn't been science to back this up.

GROSS: Another theory that you talk about in your book about the new puberty is that obesity might be linked to early puberty. What's the connection?

GREENSPAN: So people don't realize that fat tissue is a very potent hormonal organ. It's the largest gland in the body. And it converts other hormones into estrogen and estrogen-like substances. So for girls, the concern is that the more fat you have, then the more estrogen it's producing and the higher estrogen levels you have, hence earlier puberty. In addition, we're concerned that there are chemicals that may make you obese, and they may also be estrogen-like chemicals. And there are chemicals that are stored in the fat tissue that then may be released and may be more biologically active.

GROSS: So what about in boys who operate chemically different than girls do and there are different hormones that create puberty in boys than in girls? What effect does obesity have on them?

GREENSPAN: Well, given that we think that obesity raises your estrogen levels, it may not contribute to early puberty in boys. And there's some interesting data about different amounts of obesity having differing effects, so there may be a difference whether you're slightly obese or very, very obese. But there are more studies under way at the moment to determine the ultimate effect of how obesity is affecting boys' puberty.

GROSS: If you're just joining us, we're talking about early puberty and how a growing number of girls seem to be going through puberty as early as 7 or 8 years old. My two guests wrote the new book "The New Puberty." And my guests are Louise Greenspan, who is a pediatric endocrinologist and teaches at the University of California San Francisco, and Julianna Deardorff, who's a clinical psychologist who teaches at the UC Berkeley School of Public Health. Let's take a short break, then we'll talk some more. This is FRESH AIR.

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GROSS: This is FRESH AIR, and if you're just joining us, we're talking about girls who seem to be going through puberty at a very early age - like 7 or 8. My guests are the authors of the new book, "The New Puberty," Louise Greenspan, who's a pediatric endocrinologist and teaches at the University of California in San Francisco, and Julianna Deardorff is a clinical psychologist who teaches at the University of California at Berkeley in the School of Public Health. They're both working together on a long-term study of girls who go through early puberty.

Can I just ask you a question about soy? I think, like, some women with breast cancer were told to avoid soy because of its estrogen-mimicking effects - correct me if I'm wrong about this - so is soy considered a possible culprit in early puberty?

GREENSPAN: So soy is something we examined because of that. But I want to make sure people understand that there's other evidence that suggests that soy can be protective. So we know from epidemiologic studies that women who grow up in countries where they eat soy have a lower rate of breast cancer. But when they move to a country where there's less soy intake, that risk increases to the background rate. So it's not a genetic difference.

When we looked at our study, we did look at soy intake, both by asking the girls what they ate and also measuring the levels in the urine. And we found preliminary data that suggests that soy is actually protective and that higher soy intake may lead to later puberty, even when controlling for the differences in the families where there was a lot of soy intake because obviously there are differences in families that are giving their kids a lot of tofu.

So the theory would be that the estrogen-mimicking effects of soy may actually cause the body to become resistant to estrogen, that it may down-regulate the estrogen receptor so that later in life your body doesn't perceive or see estrogen in quite the same way. So we think that soy may actually be protective, and the data's now coming out that women shouldn't worry so much about their soy intake for breast cancer.

But I do think it speaks to another concept in environmental health, which is the window of susceptibility. And that means the timing of when you are exposed to something does affect the outcome. We think that children should eat soy because that's when it trains their body to become resistant to estrogen.

DEARDORFF: Yeah, and to be honest, this window of exposure is somewhat a relatively new concept when we're talking about environmental exposures because up until very recently, we didn't have the technology, the assays, to test for a lot of these things in kids' bodies at such kind of low levels because, you know, kids are different than adults. And they - the technology is now catching up, and we're able to see what the body burden is and when the timing of exposure is and whether it has effects.

GROSS: Let me throw another set of variables into the mix, variables that you think might be responsible, in part, for early puberty and that's, like, emotional factors like stress. What is some of the research telling us about factors like stress in causing early puberty?

DEARDORFF: So this is an area that will surprise most people particularly because it's no longer just hypothetical. There have been decades of studies that have shown that girls who are growing up in more unstable or unpredictable environments, families that have a lot of family conflict and low emotional warmth, those girls tend to enter puberty earlier. It's unlikely that that is the cause for puberty starting earlier and earlier over the past few decades. I think there's always been family strife and contextual strife, but certainly when all things are equal, girls who have higher levels of family conflict early in life and low - kind of low parental warmth tend to enter puberty earlier for all the markers - for breast and pubic hair development and also in terms of their first periods or menarche.

GROSS: What sense does that make?

DEARDORFF: You know, it - there's a couple different explanations. But I think the one that is most commonly discussed is kind of an evolutionary hypothesis, which is just like all the other environmental exposures that the body is sensitive to and adaptive to and malleable, if you will, during this time, emotional stress is yet another one that the body is going to adjust around. And so if a girl's physiology is such that she is preprogrammed to know that the environment is not a safe one, then it makes a lot of sense to enter reproductive processes earlier so that she can reproduce quickly in an unsafe world if you will.

GROSS: Wait, so she could reproduce quickly in an unsafe world?

DEARDORFF: That's exactly right.

GROSS: I don't understand why that would be helpful.

DEARDORFF: I know, I know. Well, if the world is not safe and stable, it doesn't make a whole lot of sense to wait. And from an evolutionary perspective, we're supposed to propagate.

GREENSPAN: For reproductive purposes.

DEARDORFF: For reproductive purposes, we're supposed propagate and continue our species, correct?

GROSS: Oh, so I was thinking - this might have nothing to with it - that, like, early puberty might have to do in that situation with being, like, mature enough to get out of the house as soon as possible.

DEARDORFF: You know, and you can take it to those lengths if you like. But it's absolutely - I mean, that's - some people have actually made those extrapolations that, yeah, if you autonomize and individuate earlier, then you can leave that unsafe environment.

GROSS: So another factor you mention in early puberty is childhood trauma, including sexual abuse. Again, what's the possible explanation?

DEARDORFF: You know, there - the jury is still out on what the explanation is. But there are numerous studies now that have confirmed the link between early sexual trauma, early sexual abuse and girls entering puberty earlier or at least getting their periods earlier. And it's shown up in study after study, and what's interesting about that finding is it even seems to be a little different from physical abuse. So there are not the clear links necessarily between physical abuse and earlier puberty, but the links are robust for early sexual trauma.

GROSS: Is that because the body thinks it's being used sexually and therefore, prepares for it?

DEARDORFF: You know, some people have suggested that. These are really hard hypotheses to figure out. What's the mechanism? Why is this happening? But that has been one of the suggestions.

GROSS: So you're saying we don't know?

DEARDORFF: We don't know. We just know it's being substantiated in the literature, but we don't know the why.

GROSS: Let's look at some of the possible consequences of early puberty. I mean, for some girls I'm sure it's no big deal, but for some girls there are some emotional problems connected to it. Do you have any idea whether it's more common to have consequences of early-onset puberty?

DEARDORFF: Yeah. It has been established that girls who enter puberty earlier are more likely to have symptoms of anxiety, higher levels of depression, to initiate sex earlier and sexual behaviors earlier and also substance use. That all sounds terrible. The really good news that has come out of the literature lately is that context really matters. So in particular, the family can serve as a huge buffer against some of those negative effects of early puberty. There's also been some research to show that certain aspects of the neighborhood context and also schools can be protective. And so that's really great news and, in fact, can completely mitigate the risk associated with early puberty on girls' emotional and behavioral functioning.

GROSS: So you think a lot of it is social and cultural - a lot of the problems connected with it.

DEARDORFF: You know, I think that there are some very real biological things going on. So, for instance, pubertal hormones do have effects emotionally on girls. They do augment emotions but so does context. And so if you're in a context that's warm, safe, stable, supportive and can kind of scaffold the girl during that time, it goes a long way towards ameliorating some of that risk.

GROSS: Doctors Louise Greenspan and Julianna Deardorff will be back in the second half of the show. Their new book is called "The New Puberty." I'm Terry Gross, and this is FRESH AIR.

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GROSS: This is FRESH AIR. I'm Terry Gross. We're talking about how a growing number of girls are entering puberty at an early age, as early as 7 or 8, and what that means for girls and their parents. My guests, Dr. Louise Greenspan and Julianna Deardorff are the authors of the new book "The New Puberty." And they're co-investigators in a long-term study of girls going through puberty. Deardorff is a clinical psychologist and is on the faculty of the University of California Berkeley School of Public Health. Greenspan is a clinical pediatric endocrinologist and is on the faculty at UC San Francisco.

I know when I was a girl and I saw some girls, like, developing breasts and, you know, growing taller and looking more mature, I really envied them 'cause they just seemed so much more, like, attractive and grown-up and everything. At the same time, it's probably really hard for them - not necessarily in terms of other girls, but in terms of the boys 'cause boys make assumptions, I think, when girls start to develop early. I think a lot of boys assume, oh, they must be sexual already. And, you know, they must be tramps or sluts or something. And those kinds of projections can be very - I would imagine could be very harmful and also some people do more than project. They hit on you.

DEARDORFF: Yeah, that's absolutely true. I think that's one of the reasons we think that girls who show early signs of puberty at very young ages get into situations that involve substance use and experimentation with sexual behaviors that they're not ready for is because they're being perceived as older. They're being perceived as more experienced, and they're being sought out after by older - not just older boys, but also older peers in general. So they end up in these peer groups that they're not ready to navigate.

But, you know, one thing that is always surprising to me is that adults in these girls' lives often also treat them as older. And so I think one really important thing is to recognize that you need to treat the girl by her chronological age and not by how her body looks. She's still a little girl and oftentimes in the body of someone much older.

GROSS: Girls go through puberty before boys typically how much sooner?

GREENSPAN: We used to think that girls on average started going through puberty around 9 or 10 and boys started around 11, so there was probably a year, maybe two-year difference. And you look in a sixth-grade class and you can pretty much see that. Now we think that the difference may be larger. So if we have 7- and 8-year-old girls starting puberty, but boys still aren't starting until 9, really 10 or 11, now it may be a three-year difference.

DEARDORFF: And where you really see these differences are in middle school. All you have to do is walk into a middle school environment. Most kids have entered puberty to some level, but the girls are so far past where the boys are.

GROSS: Tell me more about what you think the consequences of that are for girls and boys who are peers.

GREENSPAN: Well, I think we really shouldn't leave the boys out. Julie and I - one of the reasons we wrote the book was because we were going to so many Girl Scout troops and school events, and we just can't keep doing that. We really wanted to educate the girls, but we realize that the boys need to know about this and that they need to know how to talk to the girls and that it's not appropriate to comment on a girl's chest, and it's not appropriate to snap her bra, and it's not appropriate to do the things that immature boys might want to do around mature girls. And that the boys have just as much responsibility as the girls do not to body shame and to treat each other with respect. So I think one of our concerns is that in a lot of parts of the country, puberty education is not until fifth grade. And if girls are starting to go through these changes in third and fourth grade, then the end of fifth grade for both the boys and the girls is way too late to be teaching them about what puberty is. And I'm not talking about sexual education per se or sexuality; I'm talking about the changes that your body goes through with puberty. So I think we owe it to our boys to educate them as well.

GROSS: Dr. Deardorff, you work as a clinical psychologist with girls. And so when you're talking to girls about early puberty and they're like 7 or 8 and you're talking to them about, you know, intimate body issues, are they comfortable talking about it typically? Do they have the language to talk about it?

DEARDORFF: Well, I have to say my - the population that I work with is firmly grounded more in adolescence, so I talk a lot to moms of girls who are, you know, between 7 and 10 and who might be going through puberty early. So a lot of the advice I have has to do with how I coach moms to manage that transition.

GREENSPAN: I actually see girls in this age-range on a daily basis in my clinic. And there's a wide range of responses. Some girls come in having read the books and know exactly what I'm talking about. Most girls come in, and the parents actually have been embarrassed and haven't known how to talk to the girls. So for the majority of those girls, I just say you're here for a special kind of checkup, just like with your - and then I name the pediatrician's name. Kids are used to going to the doctor. They go once a year. They go every time they sprain their ankle or they're sick. So to be seeing a new doctor isn't as alarming to them I think as it is to us. And I just say, your body is growing and changing and your body is starting to change a little bit earlier than normal. And then I really name the things with the right names. And I think it's really important to be anatomically correct.

Most of the kids are not alarmed by this if we present it to them in a non-alarming way. So I think because I talk about it so much, I'm obviously talking to you about it, so I feel pretty comfortable saying the words breasts and pubic hair. I can say those words to the girls. And I often see the parents sort of sigh with relief that thank God someone's talking about this because it was hard for them to talk about it. Some of the girls are very, very embarrassed, but most of them aren't. And honestly, if we have a girl that's particularly restrictive about her body, that brings up some concerns because most kids are not that uncomfortable. And if they are really uncomfortable, then we do worry. It's a little alarm that goes off that maybe they've been touched inappropriately. But that is so rare. Most kids feel pretty comfortable.

GROSS: Why is it so important to be anatomically correct in your language?

GREENSPAN: I think it's an opportunity to teach the girls that will be young women that their bodies are healthy, that their bodies are normal, that there's nothing wrong with them. Their clock might be just a little bit fast, but I think it comes with the whole discomfort that so many adult women have with their bodies. And I really want the gift that I give these girls when they're 30 years old is that they're comfortable with all of these things. And I think that starts at a very young age. And if you send the message to the children that this is OK to talk about and this is a comfortable thing, then I hope that message stays with them when they grow up so they feel more comfortable in their own bodies.

DEARDORFF: And I think the other reason it's important is because if we start speaking in euphemisms, we're not sure that everybody's on the same page, that we're understanding things in the same way. And so calling your period your visitor or Aunt Flow can be super confusing for kids who don't have the right language around it. And how do they then communicate with each other? So we're trying to build community among girls so that they can feel empowered to talk about some of this with each other. And they need to have the right words.

GROSS: Well, I'm glad you mentioned menstruation because, you know, let's face it - a lot of women get cramps or, you know, have other problems associated with their period. And, you know, it used to be known as the curse. And I think mothers have probably, you know, gotten a lot better about talking to their children about it. But what advice do you have about how to - if you're a mother - how to tell your daughter that this thing is going to be happening to her that may seem alarming because it involves blood, but it's really normal, it's fine - even if it's uncomfortable - it's fine and normal?

GREENSPAN: I think it starts with being comfortable talking about your own period and demonstrating that, hey, once a month this thing happens. It's the only time in your life you're going to bleed without having any pain. Isn't that funny? And for a 6- or 7-year-old to start with that idea - my son knows that I get my period - so I think it's important that the girls know that this is a part of normal, healthy life and that 50 percent of the population spends a large part of their life having this. I think you should be honest that sometimes you get a little bit of a tummy ache and that's the cramps that you feel, but this is what we do to take care of that. And sometimes the week before I'm tired, and I have a lot more strong feelings and I need to make sure that I handle those feelings in an appropriate way. But that's a way to model that the girls may also have times when they feel, quote, "hormonal," which is a word I don't necessarily like. But when they feel that their feelings are stronger and harder to control, if you teach them the healthy ways of handling that during your period when you're PMSing, then you're demonstrating to them what are the healthy things to do. So, for example, I'll go for a run when I'm feeling that way. I don't want my child to think that it's healthy to binge eat or to yell or to do a lot of the unhealthy habits that people do when they're feeling those feelings.

GROSS: Let me reintroduce you both. My guests co-wrote the new book "The New Puberty." And they both study early onset puberty. They're both working together on a long-term study of girls who go through early puberty. Louise Greenspan is a pediatric endocrinologist who teaches at the University of California in San Francisco. Julianna Deardorff is a clinical psychologist who teaches at the University of California at Berkeley in the School of Public Health. Let's take a short break, then we'll talk some more. This is FRESH AIR.

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GROSS: This is FRESH AIR. My guests, Doctors Louise Greenspan and Julianna Deardorff, are the authors of the new book "The New Puberty." And they're co-investigators in a long-term study of girls going through puberty.

You know, we were talking about euphemisms in language. When you're actually teaching your children about sex, do you use euphemisms there, or do you use, like, the kind of clinical language that you recommend that parents use when describing puberty to their children?

GREENSPAN: I think it depends on the age of the child and the questions that the child is asking. This is one of those times where you answer the question being asked and you actually don't answer anything else. And I've been through this now over the years with my own children, and I've seen the way that the question has changed from when I was pregnant and my daughter was 2, which was a very different answer to when the next relative was pregnant when my daughter was 5. And now my kids pretty much know how it happens. And now they're 7 and 9, so I think you have to really go with what your child knows. But again, I don't think you need to do euphemisms. I'm careful about what I say. And funnily enough in San Francisco, there's so many different family structures that then they start asking things about like, well, fine, that's how it is with a mommy and a daddy, but what about when there's two daddies or a mommy and a mommy or - so we actually had to get into other alternative fertility even before the old-fashioned way in San Francisco.

GROSS: So I want to get back to something that, Dr. Greenspan, you were talking about - when it comes to sex, answer the question that was asked. Don't go any further when your children are young. So when you are asked about - you say, you know, how does a mommy have a baby? Or, you know, why is my aunt pregnant? What's the easiest way of saying something that doesn't get into more information than you want to describe or that your child needs to know yet?

GREENSPAN: The way that I did it, which worked well with my children, was I started with, when a man and a woman love each other very much and they're ready to have a baby, the man and the woman have a special kind of grown-up hug. This is when the kids were toddlers, and that seemed to answer their question. I don't think I'm the expert necessarily on how to teach your children about sex 'cause I'm more of the puberty person.

There are so many resources and books out there. And so what I did was I actually ordered a slew of books online and at my local independent bookstore. I just went in and bought every book I could find on the shelf and partly because I felt like I needed it anyway as a professional and for writing the book. And I looked at examples, and then I read the books with the children. And there are books for toddlers, there are books for early elementary school and there are books for middle school kids. And we do list some of those in our book because we feel that they actually do a great job of being age-appropriate and using the correct language.

GROSS: I like the very special grown-up hug thing, but then did your child ask a follow-up afterwards? (Laughter).

GREENSPAN: Oh, yeah. Every year, there's been a new question until finally ew...

DEARDORFF: Did you and dad do that?

GREENSPAN: Yep, did you and dad do that? And then the response was that - yeah - disgust.

GROSS: Right. When the reaction is disgust, what do you say to that?

GREENSPAN: I laugh. I say I know it sounds disgusting now, we'll talk about it again later.

GROSS: Good, OK.

GREENSPAN: I think one of the chapters in our book is Don't Have The Talk, Start The Conversation. And I think it's always about open lines of communication. And if you just talk to your child - and saying anything is better than saying nothing - and leaving it always open to, well, next time you want to talk about it, you know, ask me again later, then you're leaving those discussions open so that you are the first person that they come to rather than the Internet or someone at school.

GROSS: Dr. Deardorff, you give advice to parents about how to deal with puberty with their children. Can you recall for us some of the things your mother, for better or worse, told you when you were wondering about changes in your body or when she was trying to prepare you for changes in your body?

DEARDORFF: You know, my mom, bless her heart, had no guidance, I don't think, in this arena, as most women of her generation, in terms of preparing her for puberty. Yet she was really good about - and this is what Louise and I recommend - showing me, here's a pad, here's how you use it. She took it out, she took the backing off, she stuck it, you know, to the underwear to show me how it worked. We really recommend that - at least when it comes to periods - you have to, you know, show your kids where the materials are to help her and how to use them and not have those things be secret or awkward.

It was interesting, though. My mom was great in that she prepared me really early, and then I didn't get my period for ever. I was like the girl in "Are You There God? It's Me, Margaret," the Judy Blume book that many women in our generation read. And it was just like when, God? When is it going to happen? Will it be soon? But what was interesting about my story - and I never knew this, and it goes back to you asking about my mom - is that I had had cancer when I was really tiny, only a year old...

GROSS: Wow.

DEARDORFF: ...And had been exposed to monumental amounts of cobalt radiation and chemo. And my mom didn't know if I was going to develop normally or get my period. And she kept all that anxiety away from me. But when I was 14-and-a-half and finally did, I swear to God the woman had a party. (Laughter) I didn't understand why. So for everybody it's different. Everyone has a different story.

GROSS: Dr. Greenspan, can you recall some of the things your mother told you about puberty?

GREENSPAN: Yeah, my parents are both in health care, so I grew up in an environment where they just discussed the facts. They felt very comfortable about that. One of the gifts that they gave me was that they - my brother was aware of what was going on. And it just so happened that the day that I got my first period, my parents were not home, and I was at home alone with my brother. And I yelled out of the bathroom, can you get that box that's in the closet? You know, because they had this box of preparation stuff from one of the companies. And he never said a word. He just handed it. He went - he called the next-door neighbor, the 16-year-old babysitter who came over. And it was a real gift to me that my parents had prepared him so that he kind of knew how to help me, which was basically to stay out of the way and to get another woman.

But it's - I really hope that my children feel that comfort with coming to me. And I'm finding now that their friends are starting to ask me the questions. And a lot of their moms are joking that, fine, I'm just going to farm it out to you. But I do think that it is nice if you're not comfortable talking about it and you just cannot get over it, find someone who is 'cause you really don't want the message to be that this is not OK to talk about.

GROSS: What about the single fathers who have the responsibility of telling this to their daughters, or couples of gay men who have the responsibility of telling their daughters about puberty and about menstruation? Is there special advice that you have for them?

GREENSPAN: I actually - given that I work and practice at Kaiser Permanente in San Francisco, I have a fair number of single dads and gay men in my practice. And what's really wonderful is I think it goes back to it takes a village. So some of the men are comfortable. Most of them feel like they want a woman in their life to help. And they seem to have a lot of, quote, "aunties," and I think some of them are actually real aunts, biologically, and some of them are women that are very close to the girls. And I think that's really great because - to have a discussion with maybe the dad and this woman person. But I do think it's great that there can be a woman in a girl's life who she feels comfortable going to. It doesn't have to be, though, if the father really feels comfortable. But it is kind of nice because a guy's never inserted a tampon or used a pad, and it is nice for the technical details to have a woman to ask.

GROSS: Well, I want to thank you so much for talking with us about this. And Dr. Greenspan, Dr. Deardorff, thank you for talking with us about puberty.

GREENSPAN: Thanks for having us.

DEARDORFF: Thank you.

GROSS: Doctors Louise Greenspan and Julianna Deardorff are the authors of "The New Puberty." You can read an excerpt on our website freshair.npr.org. Coming up, our TV critic David Bianculli looks ahead to NBC's live broadcast of "Peter Pan" and looks back on earlier TV productions of the musical. This is FRESH AIR.

TERRY GROSS, HOST: This is FRESH AIR. On Thursday, NBC devotes all three hours of its primetime lineup to a new production of the musical "Peter Pan." Because it will be performed and broadcast live, our TV critic David Bianculli hasn't seen it, but he loves the idea of live TV making a comeback. And besides, he says, he's already seen one live TV production of "Peter Pan," and reviewed it, too.

DAVID BIANCULLI, BYLINE: Author J M Barrie created his classic characters - the ageless Peter Pan, the little girl Wendy whom he whisks away to Neverland and the villainous pirate Captain Hook - in short stories at the turn of the 20th century. Those stories led quickly to a play, then a book. But "Peter Pan" in America really took off in the '50s. Walt Disney's full-length animated "Peter Pan" movie came out in 1953, a Broadway musical production in 1954 and the first live telecast of that production in 1955 on NBC.

That TV version, like the Broadway show, starred Mary Martin, Larry Hagman's mother, as Peter Pan. It was such a hit on TV, it was performed all over again the following year - a rare event for television - and then performed live once more four years later, this time in color. The date was December 8, 1960. And I know that because my diary entry for December 7, 1960, when I was 7 years old, reads (reading) today I am too tickled because tomorrow "Peter Pan" is on. And before I went to bed the following night, I wrote what I consider one of my earliest surviving pieces of writing as a TV critic, quote, "was Peter Pan good today," unquote. And it was. Back then, NBC referred to its ambitious TV specials as spectaculars. And that version of "Peter Pan" with Mary Martin suddenly lifted into the air by wires I never noticed, certainly qualified.

(SOUNDBITE OF TV SPECIAL, "PETER PAN")

MAUREEN BAILEY: (As Wendy) Can you really fly?

MARY MARTIN: (As Peter Pan) I'll teach you.

BAILEY: (As Wendy) How lovely to fly.

MARTIN: (As Peter Pan) I'll teach you how to jump on the wind's back. And away we'll go.

BAILEY: (As Wendy) Oh.

MARTIN: (As Peter Pan) One day when you're sleeping in your silly bed, you might be flying about with me, saying funny things to the stars.

BAILEY: (As Wendy) How do you do it?

MARTIN: (As Peter Pan) You just think lovely, wonderful thoughts, and up you go.

BAILEY: (As Wendy) I'm flying. I'm flying.

MARTIN: (As Peter Pan, singing) Look at me way up high, suddenly here am I. I'm flying. I'm flying.

BIANCULLI: NBC, the network that presented the original live "Peter Pan" musical telecast, is about to do it again. NBC is still flying high from last year's live telecast of "The Sound Of Music," an experiment that drew Carrie Underwood in the central role, but was an unqualified success at attracting viewers. An estimated 22 million people watched that production, which was overseen by Craig Zadan and Neil Meron. They've already had a hand in reviving the movie musical, thanks to "Chicago" in 2002 and the big-screen version of "Into The Woods" coming later this month. But on TV what they and NBC are doing isn't it just reviving the form, it's reviving the medium.

(SOUNDBITE OF TV COMMERCIAL)

UNIDENTIFIED MAN: For one night only, everyone can fly.

ALLISON WILLIAMS: (As Peter Pan, singing) It's like flying.

UNIDENTIFIED MAN: "Peter Pan Live!" The family classic like you've never seen it before.

UNIDENTIFIED ACTORS: (As characters, singing) Are you going to get your vengeance?

CHRISTOPHER WALKEN: (As Captain Hook) Yes.

UNIDENTIFIED ACTORS: (As characters, singing) Or you need a way to kill him?

WALKEN: (As Captain Hook) Yes.

UNIDENTIFIED MAN: Christopher Walken as Captain Hook.

WALKEN: (As Captain Hook) Just little old me.

UNIDENTIFIED MAN: And Allison Williams.

WILLIAMS: (As Peter Pan, singing) I won't grow up.

UNIDENTIFIED MAN: As the boy who never grew up.

WILLIAMS: (As Peter Pan, singing) So come with me where dreams are born and time is never planned, in Never Neverland.

UNIDENTIFIED MAN: "Peter Pan Live!" Thursday, December 4 on NBC.

BIANCULLI: Casting Christopher Walken as Captain Hook in this new "Peter Pan" is a genius move. Relatively few people know him as a song and dance man or saw him in the film version of the musical drama "Pennies From Heaven." But he has the kind of credibility and audience base that should draw people to this live telecast. And in the title role, Allison Williams should, too, not because of her ability to carry the leading role in a musical, which at this point is a question mark, but because of the fans who watch her on HBO's "Girls." Add in the preteens who should be excited about watching Peter Pan fly through the air, and you have three generations of viewers with good reasons to tune in. And it's live.

When I was a kid, if you missed "Peter Pan" on TV, you really missed it. No DVDs or home-video, no cable marathons and for those first few telecasts, no reruns. That's why it was so diary-worthy. In 2014, things are different. Record it yourself or watch highlights on the Internet or the eventual home-video release, and you can enjoy this new "Peter Pan" whenever and these days wherever you want.

But there's something extra special about watching live TV, knowing that millions of others are doing the same thing at the exact same time. In the '40s and '50s, TV had to broadcast live. Today, except for sports, news, award shows and late-night comedy shows it's a rarity. And the success of "The Sound Of Music" last year suggests there's an appetite for more.

I can't wait to see this new "Peter Pan," but I'll have to because it's live. New songs are being added to the familiar ones, and the script is being adapted somewhat for modern times. But the magic is in the pixie dust. And that ought to be as potent in 2014 as when NBC first broadcast "Peter Pan" in 1955. (Reading) Dear diary, "Peter Pan" is coming on TV again. And I'm still tickled.

GROSS: David Bianculli is founder and editor of the website TV Worth Watching and has curated an exhibition on the history of television, which is on view at the apexart Gallery in New York City through December 20. Here's Mary Martin from the original Broadway cast recording of "Peter Pan."

(SOUNDBITE OF BROADWAY SHOW, "PETER PAN")

MARTIN: (As Peter Pan, singing) I won't grow up. I don't want to go to school just to learn to be a parrot and recite a silly rule. If growing up means it would be beneath my dignity to climb a tree, I'll never grow up, never grow up, never grow up - not me, not me, not me. I won't grow up. I don't want to wear a tie and a serious expression in the middle of July. And if it means I must prepare to shoulder burdens with a worried air, I'll never grow up, never grow up, never grow up - not me, not me. So there. Never going to be a man...

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