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2007-9-2 10:12:27

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Girls with excessive weight gain in their very early childhood are likely to have an earlier onset of puberty, suggesting that overweight may cause young girls to step into womanhood early, according to researchers at the University of Michigan C.S. Mott Children's Hospital.


Earlier puberty is no fun for girls to develop into as it causes a whole range of physical and psychological challenges for them to overcome in their childhood and adulthood.   For instance, girls with early puberty are likely to have a longer period of exposure to reproductive horm ones, increasing their risk for can cer.


The study published in the March issue of the journal Pediatrics shows a high body mass index (BMI) score in girls as young as age 3, and large increases in BMI between 3 years of age and first grade are both associated with earlier puberty, which was defined as the presence of breast development by age 9.


In the longitudinal study, Joyce Lee, M.D, MPH, lead author and assistant professor in the Department of Pediatrics and Communicable Diseases at the U-M Medical School and colleagues meant to examine the association between weight status and timing of puberty in girls younger than 5.


"Our finding that increased body fatness is associated with the earlier onset of puberty provides additional evidence that growing rates of obesity among children in this country may be contributing to the trend of early maturation in girls," says Lee.


Lee says the fact that girls in the United States enter puberty and develop obesity at younger ages today than their counterparts 30 years ago led them to speculate that childhood obesity may be a risk factor for earlier puberty in girls.


"Previous studies had found that girls who have earlier puberty tend to have higher body mass index, but it was unclear whether puberty led to the weight gain or weight gain led to the earlier onset of puberty. Our study offers evidence that it is the latter," says Lee.


Seeking to establish an association between weight in early childhood and the onset of puberty, Lee and colleagues went through data from 354 girls from diverse socioeconomic backgrounds in 10 regions of the United States, who participated in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development study.


In the study, girls with BMI between the 85th and 95th percentiles were defined as at risk for overweight and those with BMI greater than 95th percentile were defined as overweight.   In addition to recording BMI and weight status from ages 3 to 12, the researchers looked at multiple outcomes of puberty in girls such as breast development and their ages at the onset of menstrual periods.


The researchers observed that by fourth grade, 30 percent of the girls were either already overweight or at risk for overweight and 168 or 47% of the study participants were considered "in puberty".  By six grade, about two dozen of the girls reported having their first menstrual period.


At all ages, a higher BMI was strongly associated with an earlier onset of puberty in girls, the study found. Additionally, a high BMI change between age 3 and first grade was also correlated with earlier onset of puberty.


Previous studies have already shown girls with earlier onset of puberty are more likely to have behavioral problems and psychosocial stress, as well as experience earlier alcohol use, sexual activity, and face an increased risk for adult obesity and reproductive cancer.


Lee says future studies are needed to identify exactly how increased body fat leads to earlier puberty in girls to prevent these adverse effects.   "Beyond identifying how obesity causes early puberty, it's also important to determine whether weight control interventions at an early age have the potential to slow the progression of puberty."


In response to the study, a scientist with foodconsumer.org said the findings are important in light of the current childhood obesity and girls’ early puberty in the country.   The findings may point to a direction for the industry to develop drugs to prevent girls from entering puberty too early by controlling their body weight.


However, he pointed out that excessive body weight or fat in nearly childhood may not necessarily be the cause of earlier onset of puberty in girls.   Both overweight and early puberty may be results of overeating in the affluent country.   Experts have warned that high intake of calories and nutrients would fuel production of horm ones that promotes early puberty.


Early puberty is not a good thing for their girls and there is no doubt about it although it’s politically incorrect to call it abnormal.  In the West, puberty at age 10 or 11 is usually accepted as normal, but normal or otherwise is subject to definition b the medical circle.  With the majority of girls entering puberty at age 11, who dare say they are abnormal?  In contrast, girls in developing countries enter puberty at age 15, which explains why they have less health problems in their adulthood.   


But can we do something to prevent earlier onset of puberty in girls?  Dr. T. Colin Campbell, a distinguished nutrition professor from Cornell University, did a famous epidemiological study known as the China Study and concluded that eating too much m eat and d airy products and eating too little of plant foods may be the cause of both early puberty and childhood obesity.

For more information, visit the US NICHD study of early child care and youth development (SECCYD).



Source:

Title: "Weight Status in Young Girls and the Onset of Puberty."
Authors: Joyce M. Lee, Danielle Appugliese, Niko Kaciroti, Robert F. Corwyn, Robert H. Bradley, and Julie C. Lumeng
Pubication:  Pediatrics Vol. 119 No. 3 March 2007, pp. E624-E630
doi:10.1542/peds.2006-2188