Outcomes of FET
The
primary outcomes after FET were pregnancy outcomes consisting of
biochemical pregnancy, clinical pregnancy (CP), ectopic pregnancy,
abortion, premature delivery and live birth (LB). A biochemical
pregnancy was indicated by a serum human chorionic gonadotropin (HCG)
level ≥ 10 IU/L on day 14 after ET. A clinical pregnancy was
considered
detecting the presence of a gestational sac by ultrasonography on day 35
after ET. A diagnosis of ectopic pregnancy occurred when a developing
blastocyst was found implanted outside the endometrial cavity. Abortion
was defined as a clinical pregnancy lost before 28 weeks’ gestation.
Premature delivery was regarded as neonatal birth from the 28th to 37th
week of gestation. Live birth was considered as the delivery of any
viable neonate at 28 weeks of gestation or later.