The role of peak serum estradiol level in the prevention of multiple pregnancies in gonadotropin stimulated intrauterine insemination cycles.

The objective was to assess whether the measurement of serum estradiol (E2) level on trigger day in controlled ovarian stimulation with intrauterine insemination (COS-IUI) cycles helps lower the multiple pregnancy (MP) rate. We performed a unicentric observational study. We included all patients who underwent COS-IUI and had a subsequent clinical pregnancy (CP) between 2011 and 2019. Our main outcome measure was the area under Receiver-Operating Characteristic (ROC) curve. We included 455 clinical pregnancies (CP) obtained from 3387 COS-IUI cycles: 418 singletons, 35 twins, and 2 triplets. The CP, MP, and live birth rates were respectively 13.4%, 8.1% and 10.8%. The area under ROC curve for peak serum E2 was 0.60 (0.52-0.69). The mean E2 level was comparable between singletons and MP (260.1 ± 156.1 pg/mL vs. 293.0 ± 133.4 pg/mL, p = 0.21, respectively). Univariate and multivariate logistic regression analysis showed that E2 level was not predictive of MP rate (aOR: 1.13 (0.93-1.37) and 1.06 (0.85-1.32), respectively). Our study shows that, when strict cancelation criteria based on the woman's age and follicular response on ultrasound are applied, the measurement of peak serum E2 levels does not help reduce the risk of MP in COS-IUI cycles.