Pregnancy and perinatal outcomes following PIEZO-ICSI with vitrified-warmed single blastocyst transfer: a retrospective cohort study

OBJECTIVE: To report pregnancy and perinatal outcomes following intracytoplasmic sperm injection using a piezo element (PIEZO-ICSI) in a large Japanese cohort undergoing vitrified-warmed single blastocyst transfer. Outcomes from conventional IVF cycles were included as a reference population sharing similar ovarian stimulation and embryo transfer protocols. METHODS: This study was a retrospective cohort study conducted in two fertility centers in Japan. A total of 1,822 PIEZO-ICSI cycles from 1,072 patients aged < 40 years at oocyte retrieval were included between June 2016 and August 2023. A reference population of 1,701 IVF cycles from 996 patients was included for context. RESULTS: In the PIEZO-ICSI cohort, the clinical pregnancy rate was 49.9% (910/1,822) and the live birth rate was 38.7% (706/1,822). Among live births, the mean birth weight was 3,011.4 ± 467.9 g, mean gestational age was 38.59 ± 1.95 weeks, and congenital anomaly rate was 1.6% (11/706). These outcomes were comparable to the IVF reference population (clinical pregnancy rate 48.4%, live birth rate 37.9%, birth weight 3,022.8 ± 469.5 g, congenital anomaly rate 2.5%). The proportion of female infants was significantly higher in the PIEZO-ICSI group (53.2% vs. 43.4%; P < 0.001). CONCLUSION: PIEZO-ICSI is associated with favorable pregnancy and perinatal outcomes in women aged < 40 years.