DR. LYNNETTE LEIDY SIEVERT, of the University of Massachusetts in Amherst, Massachusetts, received funding in November 2002 to aid research on signals of ovulation in women who believe they know when they ovulate. Sievert tested whether or not women who think they know when they ovulate really do know, by assessing the concordance between perceived signals of ovulation and an elevated level of urinary LH, a biological indicator of ovulation. Participants were ages 18 to 46, had regular menstrual periods, were using no form of hormonal contraception, and believed they knew when they ovulated. Fifty-three women began the study. Signals of ovulation reported at initial interview included cervical discharge (68%), abdominal pain (64%), increased libido (30%), changes in mood or energy (25%), basal body temperature (17%), and other, infrequently reported symptoms (45%). Signal reporting varied in relation to smoking habits, body mass index, and health status. Thirty-six women provided a total of 87 urine specimens for LH testing. Thirty-seven of the specimens tested positive for an LH surge, for a concordance rate of 43%. Using the first tested cycle from the 36 women who provided urine specimens, 13 demonstrated an LH surge, for a concordance rate of 36%. The mean level of accuracy among the 15 women who contributed three to six urine specimens was 49%. It appeared, then, that between one-third and one-half of women who thought they knew when they ovulated were correct.