Abstract

Background: The transfer of cryopreserved embryos can be timed with ovulation in a natural cycle or after artificially preparing the endometrium with exogenous hormones. Progesterone is essential for the secretory transformation of the endometrium that permits implantation as well as maintenance of early pregnancy. The purpose of this study is to assess the effect of luteal phase supplementation on pregnancy rates in natural frozen-thawed cycles. Materials and Methods: The study was designed as a prospective randomized clinical trial of 102 women who underwent embryo transfers in natural cycles. The women in the interventional group (n=51) received intra muscular (IM) progesterone 50 mg twice a day starting from 36 hours after hCG administration. The control group (n=51) did not receive any progesterone support. Results: There were no significant differences in demographic characteristics between the groups and no statistically significant differences were observed between study and control groups in clinical pregnancy rate (33.3 vs. 27.5, p=0.66). There were no differences in implantation rate or spontaneous abortion rate. Conclusion: Our results suggest that luteal phase support does not affect clinical pregnancy rates in natural frozen-thawed embryo transfer cycles (Registration Number: IRCT201108044339N6).