Follicular growth in relation to serum hormonal patterns in adolescent compared with adult menstrual cycles.

The purpose of this study was to clarify the endocrine regulation of the adolescent menstrual cycle, especially the relationships between ovarian follicular development, luteal phase progesterone secretion, and function of the hypothalamic-pituitary unit. One menstrual cycle of each of 17 women who were 15 and 16 years of age and 12 women who were 25 to 35 years of age was characterized by ultrasonography and hormone measurements. In both groups there was a close correlation between follicle size and serum estradiol concentrations. In the adolescents, follicle development was slower, and an eventual ovulation took place from a smaller follicle than in the older group. The immediate preovulatory follicle size correlated with the maximal serum progesterone concentration during the luteal phase. Late follicular development in adolescents may be related to the slow increase of serum follicle-stimulating hormone concentrations early in the cycle.