Genome-wide microRNA expression profiling in placentae from frozen-thawed embryo transfer (FET)

Frozen-thawed embryo transfer (FET) is increasingly available for the improvement of the success rate of assisted reproductive technologies other than fresh embryo transfer (ET). There have been numerous findings that FET provides better obstetric and perinatal outcomes. However, the birth weight of infants conceived using FET is heavier than that of those conceived via ET. In addition, some reports have suggested that FET is associated with perinatal diseases such as placenta accreta and pregnancy-induced hypertension and a decrease in the sex ratio of male infants. These phenotypic alterations are caused by epigenetic alterations. MicroRNAs (miRNAs) are one of epigenetic modifications and dysregulation of miRNAs due to the environment in utero leads to placenta-associated diseases in infants and subsequently chronic diseases later in life. In this study, we compared miRNA expression profiles in the placentas originated from intracytoplasmic sperm injection and FET (ICSI-FET), intracytoplasmic sperm injection and ET (ICSI-ET) and from intracytoplasmic sperm injection and FET (ICSI-FET), intracytoplasmic sperm injection and ET (ICSI-ET) and spontaneous pregnancies (SP). To investigate miRNAs contribute various phenotypes of frozen–thawed embryo transfer (FET), we carried out comprehensive analysis for the miRNA profiling of human term placenta from intra-cytoplasmic sperm injection and frozen–thawed embryo transfer (ICSI-FET), intra-cytoplasmic sperm injection and fresh embryo transfer (ICSI-ET) and spontaneous pregnancies (SP).