Fresh vs. frozen embryo transfer in assisted reproductive techniques: a single center retrospective cohort study and ethical-legal implications

Abstract

OBJECTIVE: Several studies have shown higher pregnancy rates and better perinatal outcomes with frozen embryo transfers than with fresh techniques, with better results in patients with polycystic ovary syndrome (PCOS) but with a higher rate of pregnancy complications such as preeclampsia. This retrospective cohort study aims to compare the cumulative live birth rates, maternal and neonatal complications of fresh embryo transfers (ET) and frozen-embryo transfers (FET) in infertile women who underwent assisted reproduction techniques (ART) at the Azienda Ospedaliera Ospedali Riuniti (AOOR) Villa Sofia Cervello, Palermo, Italy. In addition, the authors have focused on the legislative and ethical complexities which such a procedure entails.PATIENTS AND METHODS: Out of 475 women undergoing in vitro fertilization programs from January 2017 to January 2021, 128 were enrolled; 70 patients underwent ET, and 58 patients FET. The main outcome measure was live birth rates. Secondary outcomes were clinical pregnancy, ongoing pregnancy, pregnancy loss, low birth weight (LBW), ectopic pregnancy, and obstetrical and perinatal complications.RESULTS: The cumulative live birth rates were similar between the fresh transfer (95.7%) and frozen transfer (93.1%). Biochemical pregnancy rates, clinical pregnancy, ongoing pregnancy, and pregnancy loss were similar between the groups.CONCLUSIONS: Obstetrical outcomes were not statistically different between the two groups; a higher preterm delivery rate was reported in the FET group. ET birth weights were notably lower for singletons compared to the freeze-all strategy. ET patients also had higher LBW rates, with a 2.5-fold higher rate compared to FET. No significant differences were found in cumulative live birth rates between ET and FET, which is consistent with earlier studies. FET protocols are linked to higher neonatal birth weight and lower risk of LBW than fresh ET. The ethical and legal quanda-ries inherent in such techniques, as technology moves on and outpaces current legislative frame-works, cannot be discounted.