Clinical Outcomes and Placental Pathological Characteristics after Fresh
Embryo Transfer and Frozen-Thawed Embryo Transfer with Different
Endometrial Preparation Protocols:a retrospective study
Abstract Objective: To analyse the impacts of fresh embryo transfer and
frozen‒thawed embryo transfer cycles with different endometrial
preparation protocols on clinical outcomes and placental pathology.
Design: Retrospective case‒control study. Setting: Peking University
Third Hospital. Population: A total of 3920 Single live birth
cases after in vitro fertilization/intracytoplasmic sperm injection and
embryo transfer cycles. Method: Cases were divided into the fresh embryo
transfer, natural cycle (NC)-frozen-thawed embryo transfer and hormone
replacement therapy (HRT)-FET groups, and clinical outcomes and
placental pathology characteristics were compared. Main Outcome
Measures: preterm birth, preeclampsia, postpartum haemorrhage, placenta
implantation, placenta previa, placental accreta, cervical
insufficiency, neonatal weight and placental pathology. Result:The risks
of preeclampsia, postpartum haemorrhage and preterm birth
were significantly higher in the HRT-FET group than the fresh
embryo transfer and NC-FET groups (13.42% vs 5.49% vs 5.91%, 21.7%
vs 12.1% vs 11.0%, 10.5% vs 7.7% vs 7.6%, p < 0.05).
Birth weight was lower in the fresh embryo transfer group than the
NC-FET and HRT-FET groups (p<0.05). There was no statistically
significant difference in the incidence of placental structural
abnormalities and pathological characteristics among the groups.
Conclusion: HRT-FET cycles were associated with increased maternal and
foetal complications compared to fresh embryo transfer and NC-HRT
cycles. There was no significant difference in the occurrence of
placental structural abnormalities or pathological changes among the
transfer methods. Keywords: Fresh embryo transfer; Frozen-thawed embryo
transfer; Endometrial preparation protocol; Clinical outcome; Placenta
Tweetable abstract: Different Embryo Transfer techniques influence the
clinical outcomes but not placental pathology .