TY - JOUR
T1 - Frozen-thawed embryo transfer
T2 - the potential importance of the corpus luteum in preventing obstetrical complications
AU - Singh, Bhuchitra
AU - Reschke, Lauren
AU - Segars, James
AU - Baker, Valerie L.
N1 - Funding Information:
L.R. has nothing to disclose. B.S. and J.S. received support from the Howard and Georgeanna Jones Research Foundation. B.S., J.S., and V.L.B. received support from the NICHD grant R01HD100341.
Publisher Copyright:
© 2020
PY - 2020/2
Y1 - 2020/2
N2 - The use of frozen-thawed embryo transfer (FET) has increased over the past decade with improvements in technology and increasing live birth rates. FET facilitates elective single-embryo transfer, reduces ovarian hyperstimulation syndrome, optimizes endometrial receptivity, allows time for preimplantation genetics testing, and facilitates fertility preservation. FET cycles have been associated, however, with an increased risk of hypertensive disorders of pregnancy for reasons that are not clear. Recent evidence suggests that absence of the corpus luteum (CL) could be at least partly responsible for this increased risk. In a recent prospective cohort study, programmed FET cycles (no CL) were associated with higher rates of preeclampsia and preeclampsia with severe features compared with modified natural FET cycles. FET cycles are commonly performed in the context of a programmed cycle in which the endometrium is prepared with the use of exogenous E2 and P. In these cycles, ovulation is suppressed and therefore the CL is absent. The CL produces not only E2 and P, but also vasoactive products, such as relaxin and vascular endothelial growth factor, which are not replaced in a programmed FET cycle and which are hypothesized to be important for initial placentation. Emerging evidence has also revealed other adverse obstetrical and perinatal outcomes, including postpartum hemorrhage, macrosomia, and post-term birth specifically in programmed FET cycles compared with natural FET cycles. Despite the widespread use of FET, the optimal protocol with respect to live birth rate, maternal health, and perinatal outcomes has yet to be determined. Future practice regarding FET should be based on high-quality evidence, including rigorous controlled trials.
AB - The use of frozen-thawed embryo transfer (FET) has increased over the past decade with improvements in technology and increasing live birth rates. FET facilitates elective single-embryo transfer, reduces ovarian hyperstimulation syndrome, optimizes endometrial receptivity, allows time for preimplantation genetics testing, and facilitates fertility preservation. FET cycles have been associated, however, with an increased risk of hypertensive disorders of pregnancy for reasons that are not clear. Recent evidence suggests that absence of the corpus luteum (CL) could be at least partly responsible for this increased risk. In a recent prospective cohort study, programmed FET cycles (no CL) were associated with higher rates of preeclampsia and preeclampsia with severe features compared with modified natural FET cycles. FET cycles are commonly performed in the context of a programmed cycle in which the endometrium is prepared with the use of exogenous E2 and P. In these cycles, ovulation is suppressed and therefore the CL is absent. The CL produces not only E2 and P, but also vasoactive products, such as relaxin and vascular endothelial growth factor, which are not replaced in a programmed FET cycle and which are hypothesized to be important for initial placentation. Emerging evidence has also revealed other adverse obstetrical and perinatal outcomes, including postpartum hemorrhage, macrosomia, and post-term birth specifically in programmed FET cycles compared with natural FET cycles. Despite the widespread use of FET, the optimal protocol with respect to live birth rate, maternal health, and perinatal outcomes has yet to be determined. Future practice regarding FET should be based on high-quality evidence, including rigorous controlled trials.
KW - Frozen embryo transfer
KW - natural cycle
KW - preeclampsia
KW - pregnancy outcomes
KW - programmed cycle
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U2 - 10.1016/j.fertnstert.2019.12.007
DO - 10.1016/j.fertnstert.2019.12.007
M3 - Review article
C2 - 32106972
AN - SCOPUS:85079881273
SN - 0015-0282
VL - 113
SP - 252
EP - 257
JO - Fertility and sterility
JF - Fertility and sterility
IS - 2
ER -