Value of the serum estradiol level on the day of human chorionic gonadotropin injection and on the day after in predicting the outcome in natural in vitro fertilization/intracytoplasmic sperm injection cycles.
OBJECTIVE: To predict the risk of premature ovulation and possibility of pregnancy in natural IVF/ICSI cycles on the basis of the estradiol (E2) level on the day of hCG injection and on the day after. DESIGN: A prospective study. SETTING: Hospital research program. PATIENT(S): One hundred sixty-four women undergoing 305 IVF/ICSI natural cycles. INTERVENTION(S): Serum E2 levels were measured approximately 12 h before (day 0) and 12-17 h after hCG administration (day 1). MAIN OUTCOME MEASURE(S): E2 levels on day 0 and day 1, the ratio of the day 1 to day 0 levels, and cycle outcome. RESULT(S): In cycles with premature ovulation and in conception cycles, the average E2 level on day 0 was statistically significantly higher than in other cycles, whereas the E2 ratio was statistically significantly lower. Multiple logistic regression was used to determine the connection of the E2 level on day 0 (B0 = -0.742, B = 2.147, P =.01) and the E2 ratio (B0 = -0.742, B = -3.135, P<.001) with premature ovulation. Only the E2 ratio (B0 = 0.659, B = -2.209, P =.0068) was significantly connected with conception. CONCLUSION(S): In predicting the outcome of natural IVF/ICSI cycles, the importance lies not in the E2 level on the day of hCG administration or on the day after, but rather in the E2 ratio.