Kaiser Permanente study explores ties between racial segregation and risk factors for early puberty in Black and Latinx girls
By Sue Rochman
The legacy of structural racism that shapes the conditions in many neighborhoods today may contribute to earlier puberty seen in Black and Latinx girls who grow up in less privileged areas, new Kaiser Permanente research suggests.
“The neighborhood we grow up in reflects and shapes so many aspects of our lives,” said the study’s senior co-author Ai Kubo, PhD, MPH, a cancer epidemiologist and research scientist at the Kaiser Permanente Northern California Division of Research. “This study allowed us to look at the extent to which growing up in a certain neighborhood may expose a young girl to factors that contribute to the timing of puberty. These may include experiencing chronic stress or adversities, lack of access to healthy foods, or being exposed to endocrine-disrupting chemicals.”
The study published in the Journal of Adolescent Health included more than 46,000 girls born at Kaiser Permanente Northern California (KPNC) hospitals between 2005 and 2011 from more than 2,500 neighborhoods throughout Northern California. All the girls were enrolled in the KPNC Puberty Study, an on-going study that has been following adolescent members of KPNC since 2015. Pubertal timing — initiation of pubic hair or breast development — was assessed by KPNC pediatricians at routine well-child visits starting at age 6.
The analyses found that neighborhood racial and economic privilege are strongly associated with the timing of girls’ puberty, with girls living in the least privileged communities 30% more likely to have earlier onset of pubic hair and 45% more likely to experience earlier breast development than girls from the most privileged communities.
This study allowed us to look at the extent to which growing up in a certain neighborhood may expose a young girl to factors that contribute to the timing of puberty.
— Ai Kubo, MPH, PhD
Previous studies have found that early puberty is associated with a variety of health consequences, including an increased risk for mental and behavioral health problems as an adolescent and chronic diseases, such as cancer, as an adult. Studies have also shown that Black and Latinx girls experience puberty earlier than girls of other racial or ethnic backgrounds, although it is not fully understood why.
Health impacts of structural racism
The long history of racial residential segregation in the U.S. continues to have ongoing implications for the health, wealth, and social experiences of Black and Latinx populations, as well as other marginalized groups. The researchers used an established measure called the Index of Concentration at the Extremes to quantify the relative concentration of white, high-income residents to Black, low-income residents in a neighborhood. Neighborhoods in Northern California made up of primarily white, high-income residents are considered to have the most racial and economic privilege. This study is one of the first to link inequities in neighborhood conditions to earlier pubertal timing among Black and Latinx girls relative to white girls.
“The history of racial segregation and other forms of structural racism and injustice need to be taken into account when we study health outcomes that vary by race,” said the study’s first author Julia Acker, MS, a doctoral student in epidemiology at the University of California, Berkeley. “Previous studies have identified individual factors, such as obesity, as reasons for early puberty. But by considering neighborhood privilege and the structural forces that shape it, we are moving beyond individual factors to identify a clustering of risk factors in racially segregated and economically vulnerable communities that increase girls’ risk of early puberty and other adverse health outcomes. ”
The researchers say the findings contribute to how we think about factors related to early puberty. “Understanding the drivers of the large disparities we see in the timing of puberty across racial and ethnic groups in the U.S. is the first step toward developing policies and programs that can reduce the health problems tied to early puberty in adolescents and throughout their lifetime,” said Kubo.
The study was funded by the National Institutes of Health.
Co-authors include Mahasin Mujahid, PhD, MS, and Julianna Deardorff, PhD, of the UC Berkeley School of Public Health; Sara Aghaee, MPH, of the Division of Research, and Scarlett Gomez, PhD, MPH, Salma Shariff-Marco, PhD, MPH, and Brandon Chu of UCSF.
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About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 600-plus staff is working on more than 450 epidemiological and health services research projects. For more information, visit divisionofresearch.kaiserpermanente.org or follow us @KPDOR.