LIVE BIRTH ASSOCIATED WITH PEAK SERUM ESTRADIOL LEVELS IN LETROZOLE INTRAUTERINE INSEMINATION CYCLES
This retrospective cohort study included a total of 2,368 OI-IUI cycles, from 1,557 patients, that occurred between January 2014 and July 2019. Study participants were between the ages of 18 and 46 years old, underwent OI or controlled ovarian hyperstimulation with letrozole followed by IUI, had at least one patent fallopian tube documented by hysterosalpingography or laparoscopy, confirmation of premenopausal status, confirmation of sperm in semen analysis, and a BMI < 44 kg/m2. Results from the study suggest that mean peak E2 level on day of hCG trigger or LH surge was independent of positive or negative pregnancy test after IUI (192.12 ± 98.80 vs.181.97 ± 109.69, respectively, P=.123). After adjusting for BMI, age, largest follicle diameter, and number of follicles ≥ 14 mm in diameter, live birth rate and clinical pregnancy rate were reduced in women with lower E2 levels than those with higher E2 levels at the 25th (E2 level, lower mean, 82.1 ± 19.8 pg/mL, vs. higher mean, 218.1 ± 104.4 pg/mL), 50th (lower mean, 107.4 ± 30.9 pg/mL, vs. higher mean, 259.8 ± 104.6 pg/ mL), and 75th (lower mean, 134.6 ± 47.5 pg/mL, vs. higher mean, 331.0 ± 107.3 pg/mL) percentile E2 level quartiles. Live birth rate was not significant different between cycles with an endogenous LH surge and no hCG trigger (n=96) and those where an hCG trigger medication was administered (n=2,272). Those cycles with an endogenous LH surge had a higher E2 level (229.42 vs. 181.34, P<.001) and fewer follicles ≥ 14 mm in diameter (1.28 vs. 1.70, P<.001).