the comparison of pregnancy outcomes in fresh and frozen embryo transfer: a cross-sectional study

Background: the benefits of frozen embryo transfer (fet) vs. fresh embryo transfer for in vitro fertilization (ivf) have been discussed in previous studies. objective: to determine and compare the pregnancy outcomes following fet and frozen embryos transfer in women who underwent assisted reproductive techniques.materials and methods: in this cross-sectional study, 233 women candidates for ivf/intra cytoplasmic sperm injection who referred to the kamali training medical center, karaj, iran during 2019-2020 were evaluated in 2 groups of fresh (n = 127) and frozen (n = 106) embryo transfers. the rates of pregnancy outcomes including chemical and clinical pregnancy, live birth, preeclampsia, ectopic pregnancy, still birth, and pregnancy loss were compared between groups in 3 age subgroups (< 25, 25-35, and 35-40 yr old).results: no significant difference in terms of chemical and clinical pregnancy and live birth rates were observed between groups in women aged < 25 yr. chemical and clinical pregnancy and live birth rates were significantly higher in the fet group compared to fresh group in 25-35-yr-old women (p = 0.01, p = 0.03, and p = 0.01, respectively). in 35-40-yr-old women, no significant differences were observed in terms of chemical and clinical pregnancy rates, but live birth rate was found to be significantly higher in the fet group (p = 0.02). the pregnancy loss was lower in the fet group (p = 0.038).conclusion: in conclusion, the fet method in women aged 25-35 yr significantly increases the chance of successful ivf/intra cytoplasmic sperm injection.