Main finding
From January 2012 to February 2022, a total of 3,920 cases were
collected, including 1822 fresh embryo transfer cases, 1353 NC-FET cases
and 745 HRT-FET cases. The HRT-FET group had the highest risk of
preeclampsia, cervical insufficiency and postpartum haemorrhage among
the three groups.The birth weight of neonates was higher in the FET
group than that of neonates in the fresh embryo transfer group. However,
the incidence of placental histological abnormalities in the fresh
embryo transfer, NC-FET, and HRT-FET groups was similar. The placental
pathological analysis of the submitted placentas showed that there was
no significant difference in the incidence of placental infarction,
calcification, syncytiotrophoblastic nodule hyperplasia or fibrin
deposition.