Growth curve analyses of follicular growth in the in vitro fertilization program.

A follicular growth model for natural follicular growth was used for a comparison between follicular growth in natural (unstimulated) cycles and cycles in which combination clomiphene citrate/human menopausal gonadotropin was administered for the purpose of in vitro fertilization (IVF). Further, the IVF cycles were subdivided into those cycles in which a spontaneous luteinizing hormone (LH) surge occurred, a pregnancy occurred, or no pregnancy occurred. A comparison of the growth of the dominant follicle between a natural cycle and a stimulated cycle revealed no difference in the appearance of the growth curve. However, follicular growth was initiated 2 days earlier in the stimulated cycles than in the natural cycles. When pregnancy cycles were compared with nonpregnancy cycles, a difference was observed. The cycles in which no pregnancy occurred resembled the growth pattern of the dominant follicle in cycles in which a premature LH surge was noted. These data suggest that follicular growth patterns may be helpful in predicting a favorable outcome before oocyte aspiration and may be a useful adjunct in comparing ovulation stimulation protocols.