Obstetrics and perinatal complications in Frozen Embryo transfer Versus Fresh transfer

The aim of this presentation is to compare the pregnancy and neonate outcome after fresh and frozen-thawed embryo transfer in the assisted reproductive technology(ART). The study focused on clinical and laboratory factors affecting the abnormal placentation, especially placenta Previa, in patients conceiving in the IVF program. The available evidences confirm that neonates born after frozen thawed embryo transfer had significantly higher mean birth weight than after fresh embryo transfer (ET). Moreover, the birth weight distribution in singletons was found to shift towards large for gestation (LGA) after frozen-thawed ET. On the other hand, the pregnancies after fresh ET were characterized by a higher incidence of placenta praevia and 3rd trimester bleeding. Placenta praevia was more common in IVF patients with fresh ET in a stimulated cycle than in patients with ET in a natural cycle. An important issue arose of how the ovarian hormonal stimulation relates to abnormal placentation and if the serum hormone levels interfere with in the IVF treatment results. There is higher risk of placenta previa in patients with endometriosis and in those that transfer the embryo in prepared endometrium for FET or Fresh compared with the natural cycles, though what causes this risk remains largely unknown. The animal studies showed that impaired vasculogenesis early in gestation may lead to underdevloment of placental vessels and cardiovascular development and developmental programing problems, such as intrauterine growth restriction of the fetus, resulting in long-term health consequences for the offspring, such as cardiovascular diseases that is higher in ART cycles.