Effects of a preovulatory single low dose of mifepristone on ovarian function.
OBJECTIVE
To investigate the effect of a single low dose of mifepristone on ovarian function, when administered in the preovulatory period.


METHODS
Healthy women with regular menstrual cycles were studied during two consecutive menstrual cycles. Either mifepristone or placebo was given in a randomized double-blind order when the leading follicle reached a diameter between 15 and 17 mm. Daily ultrasound and serum hormone measurements were obtained until follicular collapse. Statistical analysis was performed using Wilcoxon signed-rank test.


RESULTS
Eight women entered the study, although one woman had to be excluded afterwards from analysis because her LH surge had already appeared on the day of treatment. The LH surge was delayed from day 14 to 17 (P = 0.01). Mifepristone caused a 3-day delay in follicular collapse, occurring on day 16 in control cycles and on day 19 in mifepristone treatment cycles (P = 0.02). The median cycle length was 26 days in control cycles and 30 days in mifepristone treatment cycles (P = 0.03). Progesterone measurement 7 days after follicular collapse did not differ significantly between both cycles.


CONCLUSIONS
A single 10-mg dose of mifepristone administered during the preovulatory phase of the cycle delays the LH surge and postpones ovulation.
van der Stege
Jolande G
JG
Meander Medical Centre, Obstetrics and Gynaecology, Amersfoort, The Netherlands.
Pahl-van Beest
Elske H
EH
Beerthuizen
Rob J C M
RJ
van Lunsen
Rik H W
RH
Scholten
Piet C
PC
Bogchelman
Dick H
DH
D003283:Contraceptives, Postcoital, Synthetic / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D005498:Follicular Phase / Q000187:drug effects*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D015735:Mifepristone / Q000008:administration & dosage*; D006080:Ovarian Follicle / Q000187:drug effects*; D010060:Ovulation / Q000187:drug effects*; D018709:Statistics, Nonparametric
D003283:Contraceptives, Postcoital, Synthetic; D015735:Mifepristone; D007986:Luteinizing Hormone