Growth rates of ovarian follicles during natural menstrual cycles, oral contraception cycles, and ovarian stimulation cycles
Received 1 March 2007; received in revised form 30 October 2007; accepted 16 November 2007. published online 13 February 2008.
Objective
To compare growth rates of ovarian follicles during natural menstrual cycles, oral contraception (OC) cycles, and ovarian stimulation cycles using standardized techniques.
Healthy volunteers in research trials and infertility patients undergoing treatment at an academic institution.
Patient(s)
Women were evaluated during natural cycles (n = 50), OC cycles (n = 71), and ovarian stimulation cycles (n = 131).
Intervention(s)
Serial transvaginal ultrasonography was performed to measure follicle diameter. Day-to-day growth and regression profiles of individual follicles were determined. Mean growth rates were calculated for ovulatory follicles. Mean growth and regression rates were calculated for anovulatory follicles.
Main Outcome Measure(s)
Follicle growth rate (in millimeters per day).
Result(s)
Mean follicular growth rate was greater during ovarian stimulation cycles (1.69 ± 0.03 mm/day) compared to natural (1.42 ± 0.05 mm/day) and OC cycles (1.36 ± 0.08 mm/day). The interval from dominant follicle selection to ovulation was shorter during stimulation cycles (5.08 ± 0.07 days) compared to natural cycles (7.16 ± 0.23 days).
Conclusion(s)
Follicles grew faster during ovarian stimulation therapy compared to natural cycles or OC cycles. Greater follicular growth rates in stimulation cycles were associated with shorter intervals from selection to ovulation. The biologic effects of increased follicular growth rates and shorter intervals to ovulation on oocyte competence in women undergoing assisted reproduction remain to be determined.
Department of Obstetrics, Gynecology and Reproductive Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Reprint requests: Angela Baerwald, Ph.D., Department of Obstetrics, Gynecology and Reproductive Sciences, University of Saskatchewan, 103 Hospital Drive, Saskatoon, Saskatchewan, Canada S7N 0W8 (FAX: 306-966-8040).
Original research supported by the Canadian Institutes of Health Research, Organon Canada Ltd., Serono Canada Inc., and the R.W. Johnson Pharmaceutical Research Institute.
Portions of these data were presented at the 50th Annual Meeting of the Canadian Fertility and Andrology Society and the International Federation of Fertility Societies 18th World Congress on Fertility and Sterility in 2004.
ABSTRACT