Introduction This prospective randomized controlled trial aimed to evaluate the effect of intrauterine insemination (IUI) before frozen-thawed elective single embryo transfer (FT-eSET). Material and methods A total of 200 couples with unexplained subfertility underwent in-vitro fertilization (IVF) treatment. Patients were randomly assigned to either FT-eSET or IUI preceding FT-eSET. https://www.nutritionesplus.shop/product-category/protein-powder/