00Nov07a Early puberty (Fwd, CC)

Puberty May Be Tied to Birth Weight

http://www.salon.com/mwt/wire/2000/11/06/puberty/index.html [Not working link]

By LINDSEY TANNER

Nov. 6, 2000 | CHICAGO (AP) -- Early puberty in some girls may be linked to low birth weight, Spanish researchers say, offering a tantalizing theory that could help explain the baffling trend toward precocious sexual development.

The findings come from a study of 54 Spanish girls who showed breast development around age 8. Those who weighed 5.5 pounds on average at birth started menstruation 1.6 years earlier than those of normal birth weight.

One theory is that early puberty in these girls might be a result of the body overzealously trying to make up for lost time.

The average birth weight for girls in Spain is around 7 pounds, about the same as it is in the United States, said Dr. Lourdes Ibanez of the University of Barcelona, whose study was published in the November issue of the journal Pediatrics.

Spanish girls, like American ones, are starting sexual development at earlier ages than previous generations.

During the study period, 1986-97, puberty starting before age 9 was noted in up to 6 percent of girls in Catalonia, the region that encompasses Barcelona.

In the United States, it has been estimated that nearly half of black girls and 15 percent of white ones start puberty by age 8, showing signs of breast development or pubic hair. That is a year or two earlier than the minimum ages listed in medical textbooks.

Menstruation occurs on average at around age 12 years in Catalonia and age 12 in the United States. That is several years earlier than in the 1800s.

Some scientists have theorized that chemicals that mimic estrogen, the female sex hormone, may be to blame. These chemicals, byproducts of the breakdown of some pesticides and plastics, may wind up in food and elsewhere in the environment. Others have suggested that America's obesity epidemic may be a cause, since overweight girls tend to start puberty earlier.

Dr. Myron Genel, a pediatric endocrinologist and associate dean at Yale University's medical school, speculated that early, rapid puberty in some girls might be the body's way of compensating for undernourishment in the womb.

Development in girls who show early signs of initial puberty, such as breast growth or pubic hair, often slows, and they end up starting menstruation and reaching their full height at the same time as other girls.

But in some girls, early sexual development may be part of rapidly progressing puberty that can limit their adult height. Hormones often are prescribed to slow their development.

In the Spanish study, girls of low birth weight grew to be more than two inches shorter on average than those with normal birth weights.