Follicular growth and endocrine profiles in spontaneous and induced conception cycles.

Twenty conception cycles were tracked with ultrasound ovarian scanning from the midfollicular to midluteal phase, and simultaneous hormone profiles were obtained in 18 of the cycles. Twelve cycles were spontaneous and 8 were induced with a variety of regimens. Two of the spontaneous cycles did not have endocrine data, and in one other no follicular growth was observed, despite repeated scanning. The induced cycles did not differ significantly from the spontaneous ones in any respect except the number of follicles and the consequent estradiol (E2) levels. E2 levels per unit total follicular surface area, however, were similar in both groups and remained relatively constant throughout the late follicular phase.