Importance of Daily Sex Hormone Measurements Within the Menstrual Cycle for Fertility Estimates in Cyclical Shifts Studies

pattern commonly assumed to occur in fertility-based research, in which the LH surge is assumed to occur not more than 48 hr before the estradiol drop. These results suggest that LH tests alone are not sufficient to assign test sessions to the peri-ovulatory phase and that analyses of sex hormones are essential to identify whether the participant was tested during the peri-ovulatory phase.