Follicular growth pattern in normal-cycling Brazilian adolescents

ObjectiveTo examine the follicular growth characteristics in normal Brazilian adolescents.DesignDescriptive study.SettingAdolescent clinic in a university hospital.Patient(s)Healthy normal cycling adolescents.Intervention(s)Endovaginal ultrasound; blood samples for hormone measurement.Main Outcome Measure(s)Follicular-phase length, follicular growth rate.Result(s)The menstrual-cycle interval was 29.5 ± 1.6 days. Sixty-five percent of adolescents had follicular-phase length of ≤16 days (group 1), and nearly 35% had follicular-phase length of >16 days (group 2). In the early follicular phase, the levels of FSH, LH, and E2 were 5.1 mIU/mL, 3.0 mIU/mL, and 28.3 pg/mL, respectively. There was a mild negative correlation between FSH and follicular-phase length across the whole cohort (r = −0.464), but after analysis as a separate group, the correlation was present only in those adolescents with follicular phase lasting ≤16 days. There was no correlation between LH or E2 levels and the follicular-phase length in either group. There was good correlation between the follicular size and follicular-phase length in both groups of adolescents. The follicular growth rate was 1.11 ± 0.05 mm/d across the whole cohort, 1.33 ± 0.05 mm/d in the adolescents with follicular-phase length of ≤16 days, and 0.88 ± 0.06 mm/d in those in whom the follicular phase lasted >16 days.Conclusion(s)A long follicular phase is common in normal-cycling, healthy adolescents as a consequence of slow follicular growth rate.