Received November 15, 2019
Accepted May 31, 2020

Objective: Reproductive medicine needs to find some ways to predict pregnancy outcomes and implantation, which are non-invasive and accurate. Immunologic factors and interleukins are good choices reported in the literature. The purpose of this study was to evaluate whether or not HCG administration can modulate interleukin 1β as a successful pregnancy predictor. Methods: This is a prospective cross-sectional study involving women with regular menstrual cycles who had frozen their embryos. They prepared their endometria with letrozole and human chorionic gonadotropin (HCG). Their interleukin 1β serum levels were checked on the day of HCG administration and embryo transfer. Its value assesses pregnancy outcome. Results: We had 44 women with mean age of 32.2±5.4, and clinical pregnancy rate of 31.8%, mean interleukin 1β before and after HCG injection in women who did not achieve pregnancy was 15.82±6.68pg/ml before HCG in- jection and 18.38±13.76pg/ml on the embryo-transfer day. It was high, but not significant (p value=0.210). In those participants who had clinical pregnancy before HCG injec- tion, the mean interleukin 1β level was 17.29±7.00pg/ml and 29.72±10.41pg/ml on the day of embryo transfer, with significant changes (p value=0.001). Conclusion: HCG did increase the mean level of interleukin 1β, but it was not significant. High interleukin 1β level is a significant predictor of successful pregnancy in IVF cycles.