The age at which girls begin menstruation, termed menarche, is likely to be early if they were small babies but heavy as children, according to an Australian study.

"The relationship between birth weight and age at menarche has been controversial, and mechanisms regulating this association are unclear," write Dr. Deborah M. Sloboda and colleagues in the Journal of Clinical Endocrinology & Metabolism.

The researchers from The University of Western Australia, Perth investigated this topic in a group of girls who were followed from the time they were born in 1989-1991.

A total of 776 girls from the cohort were enrolled in the study, and 349 had had their first monthly period. This occurred significantly earlier in girls with below-average birth weight, the team found, and an above-average weight at age 8 years.

The age at menarche in girls with the lowest birth weight and the highest childhood body mass index, or BMI, was 12.5 years on average, while among those with the highest birth weight and lowest childhood BMI it was 13.2 years.

"Our findings provide further evidence that birth weight and childhood overweight may potentially compromise reproductive health in women," Sloboda and colleagues conclude.

"Early age at menarche may be a marker for early life events regulating reproductive, endocrine, and metabolic development that may manifest later in life as polycystic ovarian syndrome, the metabolic syndrome, and potentially breast cancer," the investigators speculate.

"Understanding factors determining age at menarche and pinpointing those individuals at risk for these diseases early in life may result in novel interventions or preventative strategies relevant to common diseases of adulthood," they suggest.

SOURCE: Journal of Clinical Endocrinology & Metabolism, January 2007.