The early postmenarcheal years represent a critical window of reproductive maturation. The trajectory of menstrual cyclicity and associated reproductive hormone milieu have been characterized1., 2., 3. and support that menstrual irregularity in adolescence may be associated with continued cycle irregularity, reduced fertility, and polycystic ovary syndrome (PCOS) into adulthood.4,5 However, menstrual cyclicity can be unpredictable in the first gynecological years, owing to the immaturity of the reproductive axis, and does not serve as a useful biomarker of early reproductive dysfunction.6 Ultimately, this lack of early biomarkers results in delayed diagnosis, intervention, and possible prevention of reproductive disturbances such as PCOS, which are known to manifest during adolescence.7

Ovarian morphology on ultrasonography could potentially serve as a noninvasive biomarker of early reproductive dysfunction. A variety of ovarian features, including antral follicle number per ovary (FNPO), ovarian volume (OV), stromal area, and echogenicity, have predictive power for hyperandrogenic causes of anovulation in adults,8., 9., 10. and preliminary evidence supports a role of ovarian enlargement in the identification of PCOS in adolescents.11., 12., 13. The number of antral follicles and ovarian size reflect the degree of reproductive symptomology in both adult14 and adolescent11 PCOS, and accumulating evidence supports their ability to reflect nutritional16 and metabolic status.15,16 Studies reporting the manifestation of reproductive dysfunction in early gynecological life have focused on changes beginning 1 or more years after the onset of menarche,17,18 leaving the first menarcheal year largely unexplored. These studies are also dated, did not have the benefit of modern ultrasound technology, and were conducted in non-domestic populations that may not reflect the current demographic makeup of the United States.

To that end, we have established a longitudinal cohort of US-based adolescents as part of the Ovarian Morphology in Girls (OMG!) study to resolve the trajectory of ovarian morphology alongside menstrual cyclicity in early gynecological life. Herein, we assessed the degree to which aspects of ovarian morphology correlate with reproductive and metabolic features during the first postmenarcheal year. The feasibility of transabdominal ultrasonography to assess ovarian features during this early postmenarcheal period was also determined.