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Developmental Biology - Precocious Puberty in Girls|
Family Structure Impacts Onset of Puberty in Girls
The authors believe their findings support a hypothesis that stress in early life may influence puberty onset. And, that the risk of early puberty could potentially be mitigated by interventions aimed at improving a child's wellbeing.
A team of researchers from Kaiser Permanente Northern California Division of Research, USA, found that girls who did not live with both parents from birth to age two were 38% more likely to begin their period before the age of 12 compared with girls who did live with both parents. Girls who did not live with both parents between the ages of two and six were 18% more likely than girls whose parents lived together to begin their period before the age of 12.
"Stress experienced before age two may have a stronger influence on puberty onset than stress experienced by older children.
Researchers investigated girls living with one or two parents based on electronic health record data of girl babies born between 2003 and 2010 within the Kaiser Permanente Northern California healthcare system, to examine family structure and puberty onset in girls.
The results of this study can now be used to guide healthcare interventions to identify and support girls who may be at higher risk of early puberty.
Risk Varied by Age
Out of the 26,044 girls included in the study, 2,034 (8%) lived with one parent before the age of two and 2,186 (8%) lived with one parent between the ages of two and six.
The authors found girls who did not live with both parents — from birth to age two — were 29% more likely to begin developing breasts earlier and 21% more likely to start the growth of pubic hair earlier when compared to girls who do live with both parents.
Girls not living with both parents — between the ages of two and six — were 13% more likely to start developing breasts and 15% more likely to start developing pubic hair earlier than girls who lived with both parents.
And by Racial and Ethnic Background
• Among all Black, White and Latinx girls in the study, approximately 30%, 5.6% and 9.6% lived with only one parent before age two.
• Black, White and Latinx girls who lived with one parent before the age of two were 60%, 24% and 30% more likely to develop breasts earlier than girls of similar ethnicity living with both parents.
• Girls who were Black or White who lived with one parent between the ages of two and six were 44% and 21% more likely to begin breast development early, compared to girls who lived with both parents.
• Latinx girls raised by a single parent between ages two and six were no more likely to begin breast development early than girls who lived with two parents.
Each girls' BMI did not significantly influence any association between living in a single parent household and earlier puberty onset, according to the report. However, other factors such as socioeconomic status, perceived stress, or adverse childhood events may help explain the differences.
The authors suggest infant attachment insecurity - the lack of a positive bond that develops between infant and caregiver - may be one mechanism causing girls living in single-parent households before age two to experience early puberty.
As data was taken from electronic health records detailed information on family structure, reasons for having only one parent in the household - such as divorce, single parent by choice, incarceration; as well as first period — was not available. While the study controlled for neighborhood-level household income at birth, later changes in address and therefore changes in neighborhood quality could have occurred during the girl's childhood and were not considered.
Future research will include factors such as household income and/or neighbourhood that may add independent sources of childhood stress, as potential mechanisms underlying an association between family structure and earlier age of puberty onset.
"Previous research has shown that infants living in single-parent households are more likely to display attachment insecurity compared with infants living in dual-parent households and girls with insecure infant attachment were more likely to experience early onset puberty — and also more likely to end puberty earlier."
Girls who experience early-life familial stress may have heightened risk of early puberty, which has adverse implications for adolescent and adult health. We assessed the association between household intactness and pubertal onset using a racially/ethnically diverse cohort of girls from Northern California.
A prospective cohort study of 26,044 girls born in 2003-10. Girls living with both parents from birth up to 6 years were considered to come from “intact” households while others constituted “non-intact” households. Pubertal development was measured using pediatrician-assessed Tanner staging for breast and pubic hair. Pubertal onset was defined as the transition from Tanner Stage 1 to 2+ for breast (thelarche) and pubic hair (pubarche). Menarche data was collected from routine well-child questionnaires. Weibull regression models accommodating left, right, and interval censoring were used to determine risk of earlier thelarche and pubarche, and logistic regressions were used to assess the risk of early menarche (age < 12).
Girls exposed to non-intact households before age 2 years were at increased risk for earlier thelarche and pubarche with significant effect modification by race/ethnicity, compared with girls from intact households. The associations were strongest among Black girls (adjusted hazard ratio [HR]: 1.60, 95% confidence interval [CI]: 1.29,1.98; HR: 1.42, 95%CI: 1.15,1.77 for thelarche and pubarche, respectively). There were no significant associations among Asian/Pacific Islanders. Girls who lived in non-intact households before age 2 years were also at increased risk for earlier menarche, but without race/ethnic interaction. Adjustment for prepubertal obesity did not change these associations. Associations between living in non-intact households after age 2 years and early puberty were weaker but still significant.
Exposure to a non-intact household early in life may increase the risk of early puberty in girls. Future psychosocial interventions focused on improving family cohesiveness and efforts to reduce childhood stress among families that are non-intact may mitigate these negative associations, thereby preventing future adverse health effects of early puberty and health disparities.
Sara Aghaee, Julianna Deardorff, Louise C. Greenspan, Charles P. Quesenberry Jr., Lawrence H. Kushi and Ai Kubo
The authors thank Amy J. Markowitz, JD, University of California, San Francisco Clinical and Translational Research Career Development Program, and Elaine Kurtovich, MPH, Kaiser Permanente Division of Research, for editorial assistance in preparation of this manuscript.
This study was supported by the National Institutes of Health (NIH) grants K07CA166143 and R01HD098220.
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Girls who do not live with both parents from birth to age two may be at higher risk for starting puberty at a younger age than girls living with both parents. CREDIT Hisdistani Times.