Drs. Julianna Deardorff and Louise Greenspan are co-investigators of a study showing that girls bodies are changing at an earlier age. Currently, 15% of girls under age eight are showing signs of puberty compared to 5% just 20 years ago. Why is puberty starting sooner? I spoke to Dr. Louise Greenspan, co-author of The New Puberty: How to Navigate Early Development in Today's Girls, about this and what parents and schools can do to help their girls during this transition. 

How did you meet and what made you decide to collaborate on this subject?

Julie and I met ten years ago on a study looking at girls pubertal development. We had different areas of expertise that complimented each other, we both had young daughters, and we were being asked to talk about this data over and over again. We joked about writing the book and then we met Bonnie Solow, a literary agent, and collaborated on The New Puberty. We wrote this book to help parents guide their daughters (and sons) when they are on that pathway. It’s a guide in adolescent parenting. 

Tell me about what you mean by puberty.

Most people hear puberty in girls and they think first period which is a late event in the process of puberty. Puberty in girls starts with breast and pubic hair development years before their period starts. During that time there is a lot of physical and psychological development happening over the course of a 3-4 year period.

The study outlined in your book is funded by the National Cancer Institute and the National Institute of Environmental Health Sciences. What is the link with cancer, the environment and early puberty in girls?

This study was funded as a breast cancer prevention study to look at environmental triggers of breast cancer mediated through first period and pubertal development. The data shows that the earlier you are when you get your first period, the higher your risk of breast cancer. But this doesn’t make sense hormonally. What makes more sense is when your breast development starts because this is a tremendous time of cellular change and growth in the breast tissue. We think that's the time of susceptibility that leads to breast cancer. We wanted to see which environmental exposure causes earlier pubertal development and subsequently breast cancer. 

I saw Ken Cook, CEO of Environmental Working Group, at a terrific women’s speaker series called Speak to Me. He mentioned your book and the three most powerful culprits: excess fat, social and psychological stressors, and endocrine disruptors. How does this effect early puberty in girls and how does this effect boys? 

Regarding obesity, fat tissue makes estrogen that may contribute to early puberty in girls. But in boys, who have a different hormonal process with puberty involving mostly testosterone, it can have a paradoxical effect. In terms of endocrine disrupting chemicals, it’s also a very complex situation because hormonally active agents will behave differently in boys and girls. A pro-estrogen in a girl might make her go through puberty early and might make a boy go through puberty late. It depends on the kind of chemical we’re talking about and what the activity might be. 

Ken Cook said, “We are changing the biology of our species through our little girls and we’ve given no thought to monitoring it until recently." Are other mammals also being effected?

I don’t think there is a controlled animal model that duplicates the conditions we are living in today. There are models that duplicate obesity or suspected chemicals. What we don’t have is what Ken calls a “Toxic Soup.” We do not have another model that adequately mimics this toxic soup, which includes obesity, screen time, and the sum total of issues we have evaluated in our study. 

What is the problem with the rise in early onset puberty?

Girls that go through early puberty are at higher risk for a host of problems including eating disorders, early substance abuse, early sexual activity, and depression. We wanted to give tools to parents to avoid those negative outcomes. But we do know the early you are when you get your first period you are at higher risk for a lot of problems. 

One of your studies follows 444, 6 to 8 years old girls from the San Francisco Bay Area since 2005 and an additional 800 from Ohio and New York. Media, diet, stresses and other factors vary across the world. Are girls in other countries developing this early or is this a specific to the US?

The data is suggesting this is a wide spread problem in the developed world. There is information coming out of Europe which is similar to the studies done in America. The main causes of early puberty are prevalent across the world. 

I know someone who adopted two girls from Africa. One of the girls got her period at ten. You mention African-American girls are starting puberty much sooner. Are African girls in Africa also starting puberty sooner? 

Not in the traditional parts of Africa but in they are in the more developed westernized regions. This is not a genetic phenomenon. Adopted girls are a whole separate category regardless of ethnicity because of the emotional stress in their early years of life. Early childhood experience is a predicator of early puberty and many of the girls adopted spent the first part of their lives in chaotic emotional environments leading to their adoption. That’s what is contributing to the early puberty, not ethnicity or country of origin. 

Jennifer Senior, author of "All Joy and No Fun, The Paradox of Modern Parenthood," said in an interview with me that the problem is not with the kids, it’s with parents and modern day parenting. How is parenting effecting girls?

There is a lot of emotional stress which goes into parenting. We know children who grow up without their biological father in their house are at higher risk for earlier puberty. We also know that children who grow up in an environment that lacks warmth are at risk. It's the love and limits model where your child needs to be supported and clearly loved but they also need parents that are going to be the captain of the ship. Even if it seems like they want to rule the roost they do better with limits. It’s a balancing act and they’re not going to have the ability to make a good decision. For instance, a 10 year old that looks 15 might be asked out on a date by an older boy. A parent needs to prepare that 10 year old to do what she needs to keep safe. But a 10 year old in a chaotic environment may think someone is paying attention to me and she might get into trouble. Different outcome in the same circumstance where the parents can provide the scaffolding for the girl because her prefrontal cortex is not developed enough. 

Has any information changed since the publication of your book?

There has been a fascinating study that came out two weeks ago from Harvard which looked at soda intake, which is why we wrote a NYTimes op-ed piece. It showed that even when a girl controls her BMI, the girls who drank more soda had an earlier first period then girls who drank very little soda. We were already advocating in our book not to give soda to kids anyway. In this study, soda was implicated, not juice.

Why does socio-economic matter?

It’s a marker for a lot of exposures. If you are of a low socio-economic status, you are more likely to live near a factory or freeway and less likely to have access or afford fresh fruits and vegetables. You may not be able to put your child in sports and the local school may not have PE everyday. Socio-economic effects a wealth of other things that we as a society should look at from a policy standpoint. My patients agonize over what to spend their limited budget on. You can feed a family cheaper on rice, lentils and frozen vegetables then fast food. People don’t always realize how expensive fast food meals get but it is quick and easy so it is appealing.

How can a parent navigate the complexities of an adolescent girl taking medication that causes weight gain and other issues?

We need to work on helping girls realize they can be healthy at any size. It's really important to know it’s about health not weight. If a child is gaining weight from a life sustaining medication they can be healthy in other ways. They don’t have to be skinny and will be healthier then other girls who are skinny but eat unhealthy food. Focus on health rather then size.

Changes in a girls body is a tough subject to broach for a father. What ways can a father help support his daughter(s) as they navigate this very complicated time?

Fathers need to find closeness emotionally with girls in other ways. Keep hugging your daughters because girls shouldn’t be ashamed of their changing bodies. Having special fathers-daughter activities that they do together helps maintain the emotional closeness. 

Can you demystify the media’s sensationalized reporting on early puberty as an epidemic in girls sexuality? 

We really tried to un-sensationalize what the media portrays. Adults link puberty to sex and kids don't. A seven year old with public hair is not leaping towards sex, she’s just got hair. In our book, we talk about "puberty parties,” a way to get together to discuss changes with mothers and girls. We talk about their changing bodies, body odor, bras, periods but not about pregnancy and sex. In 6th grade you might talk about sex and what sex is. In 8th grade you might bring that up again and talk about safe sex and condoms. In 10th grade you might talk about healthy sex and relationships. You have to take a developmental approach to this topic and see it in their perspective.

Louise Greenspan, MD, a pediatric endocrinologist focusing on puberty and an international leader in the field, works at Kaiser Permanente and is on the faculty at UC San Francisco. The book, The New Puberty: How to Navigate Early Development in Today's Girls, is on sale now. Learn more on Twitter at @Thenewpuberty, Facebook, and on thenewpuberty.com.