fa Embryology Embryology پژوهشي Original Research <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Background:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> Implantation failure in assisted reproductive technologies (ART) remains a challenge. Granulocyte-macrophage colony-stimulating factor (GM-CSF) may enhance embryo implantation, but its efficacy needs more investigation. This study aimed to assess if adding GM-CSF to thawed embryo culture could improve implantation rates in frozen embryo transfer cycles.</span></span></span></span></span></span><br /> <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Methods:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> One hundred rats were randomly assigned to GM-CSF or control groups at Avicenna Infertility Clinic, Tehran. Control group had standard embryo culture; GM-CSF group had embryos cultured in Embryogen&reg; with GM-CSF. Pregnancy outcomes were assessed via serum &beta;-HCG levels post frozen embryo transfer (FET) and ultrasonography at gestational week seven.</span></span></span></span></span></span><br /> <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Results:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> No significant difference in blastocyst formation rates was found between groups. Positive beta-HCG levels were 36% in control and 40% in GM-CSF groups. Gestational sacs were detected in 36% of control and 34% of GM-CSF group during weeks 5-6. Clinical pregnancy rates were 32% in control and 30% in GM-CSF groups.</span></span></span></span></span></span><br /> <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Conclusion:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> GM-CSF in embryo culture of thawed embryos shows no significant impact on blastocyst formation or pregnancy outcomes. However, interventions like these may enhance fertility treatments, warranting larger-scale clinical trials for further exploration.</span></span></span></span></span></span> Assisted Reproductive Technologies (ART), Frozen embryo transfer (FET), Granulocyte-macrophage colony-stimulating factor (GM-CSF), Implantation rates, Clinical pregnancy 1 7 http://caspjrm.ir/browse.php?a_code=A-12-143-2&slc_lang=fa&sid=1 Simin Zafardoust siminzafardoost@yahoo.com 10031947532846002359 10031947532846002359 No 1Nanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran Mohammad Reza Sadeghi 10031947532846002360 10031947532846002360 Yes Farnaz Fatemi 10031947532846002361 10031947532846002361 No Sheyda Jouhari 10031947532846002362 10031947532846002362 No Afsaneh Shahbakhsh 10031947532846002363 10031947532846002363 No Azam Mohammad Akbari 10031947532846002364 10031947532846002364 No Zohre Fathi 10031947532846002365 10031947532846002365 No Zahra Sehat 10031947532846002366 10031947532846002366 No Narges maleki 10031947532846002367 10031947532846002367 No