Women's Health Q&A

Text Size: Normal / Medium / Large
Printer-friendly versionPrinter-friendly version

Women's Health Q&A
Complied by Barbara Bourrier-LaCroix

Is the environment having an effect on puberty in girls?

Menarche, the first menstrual period, normally occurs between ages ten and sixteen, generally several years after the first signs of puberty appear. These include widening of the hips, breast development and body hair growth. By the time menarche takes place, most young women have nearly completed their growth spurt and are within a few centimetres of their adult height. Precocious—or early—puberty occurs in girls who show signs of sexual development before age eight.

A study published in the American journal Pediatrics in 1997 found that the initial signs of puberty (breast development and the appearance of pubic hair) are occurring earlier than previously recorded, as early as ages six or seven. However, the average age of menarche (first menstruation) seems to have remained the same—twelve years of age. While the study has been criticized, many experts and scientists are looking for explanations. To date, the three most popular theories for cause include obesity, social factors and chemicals in the environment.

Many studies have looked at links between nutritional status, weight and timing of sexual development. Some show early puberty occuring among obese girls and delayed puberty in very thin girls. Other studies consider the impact of family environment on sexual development with one concluding that girls growing up in stressed families reach puberty earlier. Another suggests that earlier puberty can occur in father-absent familes, or in families where an adult male who is not the girl's genetic father is present.

Common belief, not born out by scientific fact, is that the increasingly overt sexuality of popular media might stimulate early development. As well, data from numerous studies done on animals show that their sexual development can be influenced by various chemical contaminants, such as PCBs, to which they are widely exposed. Some epidemiologic studies and medical case histories suggest that sexual development in people can be affected by environmental contamination.

The Pediatrics study has led some to suggest changes in the guidelines used by pediatricians to evaluate early puberty in girls. Others worry that if doctors assume girls who start developing at six or seven years of age are normal, they might miss serious medical problems like tumours or genetic disorders.

It is known that early puberty can decrease a girl's ultimate height. Perhaps more troubling than such physical effects is the concern that young children are emotionally unprepared for puberty with its accompanying mood swings, hormonal changes and the sexual attention that physical maturation attracts. Studies have found affected girls tend to have sex at younger ages, to experience more psychological stress and are more likely to drink and/ or smoke.

The debate continues. Meanwhile, girls who show signs of early puberty should be examined by a doctor to rule out any serious medical conditions.

Source — Our Stolen Future www.ourstolenfuture.com/NewScience/reproduction/Puberty/pubertydebate.htm

Questions about women's health?

Toll-Free: 1-888-818-9172
Ph: (204) 942-5500
Fx: (204) 989-2355
TTY in Winnipeg: 942-2806
TTY Toll Free: 1-866-694-6367
Email: questions@cwhn.ca