Opposing influences of prenatal and postnatal growth on the timing of menarche.

CONTEXT AND

OBJECTIVE

Menarche is a milestone of reproductive development, and its timing may be differentially influenced by the growth conditions before birth and those between birth and puberty. The present study explored the relationships among menarcheal timing and markers of prenatal and midchildhood growth in healthy Australian girls.

SETTING, DESIGN, AND PATIENTS: A total of 156 girls aged 8 yr from a birth cohort of full-term babies had height, weight, and waist circumference measured. One hundred three girls had dual x-ray absorptiometry performed and blood analyzed for insulin, leptin, IGF-I, estradiol, and dehydroepiandrosterone sulfate levels. Girls were followed up at age 15 yr and their age of menarche was recorded.

MAIN OUTCOME MEASURES: Measures included age of menarche; birth weight and birth length; height, weight, waist circumference, and body composition by dual x-ray absorptiometry; and plasma insulin, leptin, IGF-I, estradiol, and dehydroepiandrosterone sulfate at age 8 yr.

RESULTS

Girls with earlier menarche were light and long at birth and had higher total and central adiposity and IGF-I and estradiol levels in midchildhood, compared with those with later menarche. Age of menarche was best predicted by combining size at birth and body mass index z score at age 8 yr (r2 = 0.12; P < 0.001).

CONCLUSIONS

The timing of menarche appears to be influenced in opposing directions by pre- and postnatal growth. Menarche was found to occur earlier in girls who were long and light at birth and who had a higher fat mass and circulating IGF-I in childhood. These findings may partly explain ethnic differences and secular trends in the age of menarche.