M Janan - Department of Genetics, Faculty of Sciences and AdvancedTechnologies in Biology, University of Science and Culture, Tehran,Iran
F Hassani - Department of Embryology, Reproductive Biomedicine ResearchCenter, Royan Ins titute for Reproductive Biomedicine, ACECR,Tehran, Iran
P Eftekhari-Yazdi - Department of Embryology, Reproductive Biomedicine ResearchCenter, Royan Ins titute for Reproductive Biomedicine, ACECR,Tehran, Iran
F Ghaffari - Department of Endocrinology and Female Infertility, ReproductiveBiomedicine Research Center, Royan Ins titute for reproductiveBiomedicine, ACECR, Tehran, Iran
SH ZareiMoradi - Department of Genetics, Reproductive Biomedicine ResearchCenter, Royan Ins titute for Reproductive Biomedicine, ACECR,Tehran, Iran
S Vesali - Reproductive Epidemiology Research Center, Royan Ins titute forReproductive Biomedicine, ACECR, Tehran, Iran

Background: The incidence of ectopic pregnancy (EP) after invitro fertilization/intracytoplasmic sperm injection (IVF/ICSI)is about ۲.۵-۵ times that of natural conceptions; however, theetiology of this increased risk remains uncertain. A sugges tedpractice change to reduce the incidence of EP is the transfer offrozen ET (Embryo Transfer) rather than the transfer of freshET. There is also variation in the reported incidence of EP followingfrozen ET. A retrospective s tudy was conducted to comparethe risk of ectopic pregnancy after frozen ET with freshET in women who underwent IVF/ ICSI and became pregnantbetween ۲۰۱۵ and ۲۰۲۰.Materials and Methods: Research conducted at Royan researchins titute during the period October ۲۰۱۵ to March ۲۰۲۰examined women who underwent IVF and ICSI treatments.SPSS software version ۲۵ is used to analyze the data. The oddsratio was calculated using MedClac software with a ۹۵% confidenceinterval.Results: Among ۲۱۲۰۳ ET cycles, ۷۶۵۸ (۳۶.۱۱%) pregnancieswere clinical, of which ۳۱۸۹ (۳۲.۷%) were fresh ET and ۴۴۶۹(۳۹.۰۲%) were frozen ET. Of all the pregnancies, ۱۳۱ (۱.۷۱%)were ectopic. Among ۱۳۱ ectopic pregnancies, there were ۶۷(۲.۱%) EPs from fresh ETs and ۶۴ (۱.۴۳%) EPs from frozenETs. The odd ratio of EP was ۱.۰۹۶ more in fresh cycles thanfreeze cycles (CI۹۵%: ۰.۶۸ to ۱.۷۸, P= ۰.۷۱۱).Conclusion: Based on our s tudy, frozen ET reduces the numberof ectopic pregnancies compared to fresh ET. In patients with ahis tory of ectopic pregnancy or those who have risk factors forectopic pregnancy, a frozen embryo transfer is generally recommended.

Ectopic Pregnancy, Embryo Transfer, Fresh EmbryoTransfer, Frozen Embryo Transfer