Retrospective Comparison of Pregnancy Outcome of Infertile Patients After Fresh and Warmed Single Blastocyst Transfer From 2014 to 2018.

Previous studies that analysed pregnancy outcomes in women who underwent frozen single blastocyst transfer have shown an increase rate of large for gestational age and very large for gestational age (Zhang et al., 2019),increased maternal risks of placenta accreta and pregnancy-induced hypertension (Ishihara et al.,2014),and lower risks of placenta previa, placental abruption, very pre-term birth, small for gestational age, and perinatal mortality (Sha, Yin, Cheng,\& Massey, 2018) than fresh blastocyst transfer. The main outcome of this study is to analyse the rate of live births with the relative gestational period and neonatal weight and still death and neonatal death per each single blastocyst transfer, both fresh and warmed. Secondary outcomes include the incidence of obstetric pathologies, gestational diabetes and pre-eclampsia, and defects of placentation. The study database included all pregnancies occurred after both a single fresh and warmed blastocyst transfer between the five-year period from 2014 to 2018 at Humanitas Fertility Centre. The inclusion criteria were all patients, without any age limitations, which underwent either FIVET or ICSI and only transferred a single blastocyst. With regards to exclusion criteria, the following were considered: ovodonation, suspended cycles and embryos which were subjected to pre-implantation genetic testing.The investigator performed a comparison of maternal and neonatal outcomes in these pregnancies which occurred in the same period of time and in the same age-group of women.