Anovulation and monophasic cycles.

Normal pubertal development is often considered complete when the adolescent experiences her first menstrual period. However, sexual maturity is not attained until the onset of regular ovulatory cycles, which may take a number of months to years to accomplish. This maturation process is orchestrated by a neuroendocrine cascade and modified by autocrine and paracrine events in the ovary. The control of these complex relationships takes time and could not be expected to be fully functional with menarche. During the first menstrual months, the hypothalamic-pituitary-ovarian axis is immature, resulting in the secretion of only estrogens from the developing follicles; positive feedback to trigger ovulation develops later. Consequently, estrogen secretion is variable and unopposed by progesterone, which would normally be produced in ovulatory cycles. Estrogen-only primed endometrium often leads to irregular menstrual cycles with variable flow. Surprisingly, most adolescents do well and have few complaints in spite of these anovulatory cycles. If an abnormality is experienced with the menstrual cycle, once understood physiologically, it can be managed simply, by watchful expectancy or intermittent progestin therapy. Occasionally, sever menstrual bleeding is encountered, and in a proportion of these patients a thorough assessment will delineate an underlying medical problem that needs to be addressed. The management of these patients requires ingenuity from the pediatric reproductive endocrinologist and aggressive hormonal manipulation. Most patients do well, but some require long-term continuing care.