FRI422 The Fates Of Ovarian Dominant Follicles In The First Two Gynecologic Years: An Investigation Of Morphologic And Endocrinologic Features

Disclosure: M. Calvert: None. S. Molsberry: None. S. Denslow: None. H. Vanden Brink: None. M.E. Lujan: None. N. Shaw: None. Introduction: Irregular menses are common during the early, post-menarchal years owing to the immaturity of the hypothalamic-pituitary-ovarian axis. Few studies have attempted to delineate the factors that contribute to cycle irregularity during this time. In the current study, we aimed to characterize the fate of ovarian dominant follicles in a longitudinal cohort of healthy, early post-menarchal girls. Methods: Participants contributed daily urine samples for reproductive hormone profiling (Cr-corrected LH, estrone conjugates [E1C], and pregnanediol-3-glucuronide [PdG]), and underwent periodic transabdominal ultrasound scans and body composition analysis. The current analysis includes cycles: 1) with an LH surge and ultrasounds performed 1-9 days before and/or <11 days after the surge, or 2) without an LH surge but with ultrasound documentation of a dominant follicle. LH surge requirements were > 40 mIU/mg Cr with concentrations > mean+3sd of the preceding 5 days. Ultrasounds were evaluated offline by two investigators using a standardized rubric for ovarian structures. Results: 26 participants contributed 74 ultrasound scans, spanning 45 cycles. Participants were 12.6 (range 9.8-14.7) years-old, 2.7 (range 0.3-9.6) months post-menarche, predominantly non-Hispanic White (65.4% vs. 26.9% Black, 3.8% Asian, 3.8% Multiracial), and of normal weight (76.9% with BMI <85th percentile). In 41/45 cycles, there was morphological (antral follicle diameter > 10 mm observed ultrasonographically, n=22) and/or endocrinological (LH surge, n=38) evidence for the presence of a dominant follicle. In 4/45 cycles, a dominant follicle was observed but peak LH did not meet LH surge criteria. In 17/41 cycles, dominant follicle fate could not be determined for technical reasons. In the remaining 24/41 cycles, dominant follicles fates post LH-surge were: corpus luteum (CL, 15/24, 71%), CL or luteinized unruptured follicle [LUF] (2/24, 8%), persistent dominant follicle (3/24, 13%), or no structure observed, implying follicular regression/collapse (4/24, 17%). In logistic GEE models, there was no association between peak E1C or LH, follicular phase length, gynecologic age, or free testosterone with odds of having a CL versus any other dominant follicle outcome. There were marginally significant associations between peak PdG (OR: 1.0003, 95% CI: 0.9999, 1.00008) and total body fat percent (OR: 0.86, 95% CI: 0.74, 1.01) with odds of having a CL versus any other dominant follicle outcome. Conclusion: In the first two gynecologic years, dominant follicles develop in most cycles and frequently ovulate. A variety of mechanisms, however, contribute to anovulation, including an absent LH surge, the formation of LUFs, and follicle regression. Whether degree of adiposity is related to ovulatory success of a dominant follicle early in gynecological life will be pursued in future research. Presentation: Friday, June 16, 2023