Pharmacodynamics of progesterone women, this effect being the result of suppression of the mid-cycle surge in gonadotropin secretion, is 300 mg/day. However, this figure is based on limited clinical data. Conversely, treatment with a high dosage of oral progesterone of 100 mg four times per day (or 400 mg/day total) in men for 10 days that resulted in approximately mid-luteal phase levels of progesterone (7.9–9.4 ng/mL; measured by ) did not cause any change in testosterone levels, suggesting that progesterone has little or no antigonadotropic effect in males at typical clinical dosages. In addition, a study found that administration of 1,000 mg/day oral
Menstrual synchrony there was no evidence the women in this study synchronized their menstrual cycles. Ziomkiewicz conducted a study with 99 Polish college women living in two dormitories. Thirty six of the women lived in 18 double rooms and sixty three lived in 21 triple rooms. Women recorded their menstrual cycle onsets on menstrual calendars provided to them and 181 days' worth of menstrual cycle data were collected. The mean menstrual cycle length was 30.5 days (SD = 4.56). Based on the mean cycle length of the women in this study, the expected difference by chance in menstrual cycle onset was approximately