Girls in late stages of puberty who had elevated levels of body fat showed unusually high levels of several hormones that could contribute to an earlier age of menarche and also slow breast development, according to data from 90 girls who spanned a wide range of body fat in the first longitudinal study to examine links between fat volume, levels of reproductive hormones, and clinical manifestations of hormone action during puberty.
Dr. Natalie D. Shaw
The results showed that girls with greater body fat had higher levels of follicle stimulating hormone, inhibin B, estrone, and certain male-like reproductive hormones, and that this pattern “is specifically tied to body fat,” said Natalie D. Shaw, MD, senior investigator for the study, reported at the annual meeting of the Endocrine Society.
“We found that total body fat is associated with the timing of menarche, as others have reported for body weight,” she noted. The new findings showed that every 1% rise in percent total body fat linked with a significant 3% rise in the likelihood of menarche, menstrual onset. In the new study the average age of menarche was 11.7 years among the overweight or obese girls and 12.8 years among those with normal weights.
But the study’s unique use of an average of about three serial ultrasound breast examinations of each subject during an average 4 years of follow-up also showed that higher levels of body fat linked with slowed breast development in later stages, specifically maturation from stage D to stages D/E and E.
For example, girls with 33% body fat spent an average of 8.2 months in stage D, which stretched to an average of 11.2 months among girls with 38% body fat, reported Madison T. Ortega, a researcher with the Pediatric Endocrinology Group of the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., who presented the report at the meeting.
Ultrasound shows what inspection can’t
Results from “several studies have shown earlier breast development in overweight and obese girls by inspection and palpation,” but the new findings from ultrasound examination provide more nuance about the structural breast changes actually occurring in these adolescents, said Dr. Shaw, who heads the Pediatric Endocrinology Group. The current study “was not designed to capture the onset of breast development,” and “it is possible that increased androgens or insulin resistance in girls with higher body fat interferes with normal breast development,” she explained in an interview.
“The authors showed that the timing and progress of early stages of puberty were not earlier in overweight or obese girls. Luteinizing hormone, the indicator of neuroendocrine pubertal onset, and timing of early stages of breast development were the same in all weight groups. The authors also discovered falsely advanced Turner breast stage designations with ultrasonography in some girls with obesity. This might suggest that prior findings in epidemiologic studies of an earlier start to puberty based mostly on breast development stages identified by self-reported inspection and, rarely, palpation, may have been biased by breast adipose tissue,” said Christine M. Burt Solorzano, MD, a pediatric endocrinologist at the University of Virginia in Charlottesville, who was not involved in the study.
“Development of increased follicle-stimulating hormone in late puberty suggests that pubertal tempo, not onset, may be increased in girls with obesity, and goes along with earlier menarche. Their finding of increased androgen levels during mid to late puberty with obesity are consistent with prior findings,” including work published Dr. Burt Solorzano and her associates, she noted. “Delayed timing of advanced breast morphology was unexpected and may reflect relatively lower levels of progesterone in girls with obesity,” a hormone necessary for later stages of breast maturation.
The findings “reinforce that early breast development in the setting of obesity may in fact reflect adipose tissue and not be a true representation of neuroendocrine precocious puberty,” Dr. Burt Solorzano said in an interview. The findings “also suggest that pubertal initiation may not happen earlier in girls with obesity, as has been thought, but rather the tempo of puberty may be more rapid, leading to earlier menarche.”