Teenagers who have irregular periods are more likely to be overweight and obese and to have early warning signs of diabetes and heart disease than those with regular menstrual cycles, suggests a new study.

While the link between irregular periods and heart disease and diabetes is well established in older women, the new finding suggests that doctors might be able to identify this risk much earlier - and try to do something about it.

“There may be a misconception in adolescent medicine ... that ‘it takes a couple of years after menarche to get the engine running’ and hence one might not want to be concerned about irregular adolescent menstrual cycles until much later,” said Dr. Charles Glueck, one of the study’s authors from the Cholesterol and Metabolism Center at the Jewish Hospital of Cincinnati.

“That’s clearly wrong.”

Even in young teenagers, very irregular menstrual cycles are not normal, Glueck told Reuters Health, and shouldn’t be ignored.

He and his colleagues followed 370 girls starting at age 14 as part of a larger study initiated by the National Heart, Lung, and Blood Institute.

Once every year, girls were asked how long it had been since their last menstrual cycle. Researchers also periodically measured their levels of different sex hormones, glucose and insulin (markers of diabetes risk) and blood pressure.

They also collected information on girls’ height, weight, and waist circumference.

The authors defined irregular menstrual cycles as lasting more than 42 days - that is, the girl’s period begins more than 42 days after the first day of the last one - a criterion that’s meant to catch the 2 percent of girls with the least regular periods, Glueck explained.

Between age 14 and 19, 269 of the girls reported regular periods at every annual visit. Another 74 of them had only one report of an irregular period, 19 girls had two reports, and eight said it had been at least 42 days since their last period at three or more visits.

The results, published in Fertility and Sterility, show that girls with the most reports of irregular periods were already heavier than others at age 14, and gained more weight and inches on their waist during the study.

Also at age 14, girls with more irregular periods had higher levels of testosterone - a sex hormone associated with male characteristics.

By age 25, those who hadn’t reported an irregular period had an average body mass index, or BMI, of 26.8 - considered slightly overweight. In comparison, participants who had reported irregular periods at three or more appointments had an average BMI of 37.8, indicating severe obesity. Girls who reported one or two irregular periods had BMIs somewhere in the middle.

Reports of irregular periods were also linked to higher levels of blood sugar and insulin at age 25.

The authors couldn’t be sure what was happening with girls’ menstrual cycles during the rest of each year. Also, the findings do not prove that irregular periods cause girls to gain weight or are responsible for the increases in glucose and insulin levels - rather, the irregularity could be a signal of some other problem.

One possibility is that the ovaries might respond to changes in metabolism - such as increased insulin levels, said Dr. Alice Chang, an endocrinologist at UT Southwestern Medical Center. That would suggest some of the diabetes-related risks came before problems with ovulation.

What the study results do show is that irregular menstrual cycles might be a warning that the body’s metabolism isn’t working as well as it should.

“These relationships which we see so clearly in adolescence and see prospectively into young adulthood are the same relationships which two to three decades later spell out in the development of cardiovascular disease, (heart attack), and type II diabetes,” Glueck said.

Irregular periods might be a sign of polycystic ovary syndrome, or PCOS - a hormonal disorder that’s also linked to infertility and obesity - Glueck added. Catching it in adolescence means the condition can be “very successfully treated” - another reason for doctors to pay attention to irregular periods early.

Chang, who was not involved in the new research, agreed that the implications for PCOS are an important message to take from the study.

“When I see women diagnosed with PCOS, they often have symptoms all throughout adolescence, but it’s not put together for them,” she told Reuters Health. “We need to be more aggressive in adolescents about treating PCOS and treating obesity.”

Glueck said that girls with irregular menstrual cycles should “raise flags” for doctors, who can also step in with early prevention measures against diabetes, obesity, and heart disease.

SOURCE: Fertility and Sterility, online May 7, 2011.