comparison of pregnancy outcomes in delayed frozen embryo transfer and immediate transfer: statistical study

Background objective: ovarian invitro fertilization (ivf) is the best treatment for couples with multifactorial infertility. controlled ovarian stimulation (cos) is the main factor for determining the success of invitro fertilization (ivf). frozen-thawed embryo transfer (fet) is performed to overcome supra-physiological hormone concentration of this process. embryo transfer can be done immediately in the first menstrual cycle or delayed two or three cycles. the present study was performed with the aim of comparing pregnancy outcomes in immediate and delayed fet after cos.materials methods:  this quasi-experimental interventional epidemiological study was performed on 202 infertile women aged 20-40 years who underwent puncture at the fertility center from 2021 to 2022. the subjects were randomly divided into two groups: immediate transfer group (n=100) and delayed transfer group (n=102). then, the rate of chemical pregnancies, clinical pregnancies, live births, implantations, and abortions were compared between the two groups by chi-square and mann-whitney tests. p<0.05 was considered statistically significant.results: successful chemical pregnancy rate was 45% in the immediate transfer group and 40.2% in the delayed group (p=0.490). the live birth percentage was 33% in the immediate transfer group and 30.3% in the delayed group (p=0.482). the number of days of estradiol prescribed for the endometrial thickness to reach the threshold of 7 mm for embryo transfer was more in the immediate transfer group (p=0.032).conclusion: there was no significant difference between the immediate and delayed frozen embryo transfer groups regarding fertility success percentage, but the only difference was in the number of days of estradiol administration.