Clinical trial NCT06181305: Endometrial Preparation in Frozen Embryo Transfer Cycles
Official title: Hormonal Replacement Therapy Plus Letrozole Incorporation Versus Letrozole Mild Ovarian Stimulation in Endometrial Preparation for Frozen Embryo Transfer: A Randomised Controlled Trial
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: PHASE4
Conditions: IVF
Lead sponsor: Rahem Fertility Center
Sponsor class: OTHER
First posted: 2023-12-26
Enrollment: 210
Sex: FEMALE
Minimum age (years): 18
Maximum age (years): 37
Standard ages: ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: In order to get optimal pregnancy rates after frozen embryo transfer (FET), the embryo stage and endometrium should be synchronized. Endometrial preparation is done by either natural, artificial (Hormonal replacement therapy HRT) , modified natural methods or mild ovarian stimulation. HRT cycle has a better schedualization however, there are some reports about higher rates of miscarriage, pregnancy induced hypertension (PIH) and preeclampsia (PET) in HRT cycles. A recent study has found that incorporation of the aromatase inhibitor (letrozole) to HRT cycles was associated with better FET outcomes in comparison to hormonal replacement therapy cycles alone. Meanwhile, mild ovarian stimulation protocol can be done either by oral drugs like letrozole or by letrozole plus gonadotropins . So this study aims to compare the reproductive outcomes in two endometrial preparation protocols for frozen embryo transfer cycles; letrozole mild ovarian stimulation versus HRT plus letrozole incorporation.

Detailed description: In order to get optimal pregnancy rates after frozen embryo transfer (FET), the embryo stage and endometrium should be synchronized. This can be done by hormonal replacement therapy (HRT), natural cycles (NC), modified natural cycles or mild ovarian stimulation. In hormonal replacement therapy cycle, estrogen and progesterone are sequentially given to resemble the hormonal course of the natural cycle . Hormonal replacement therapy cycle has a better schedualization and is used for patients with irregular cycles as polycystic ovary syndrome ( PCOS). However, there are some reports about higher rates of miscarriage, pregnancy induced hypertension (PIH) and preeclampsia (PET) in HRT cycles.

A recent study has found that incorporation of the aromatase inhibitor (letrozole) to HRT cycles was associated with better FET outcomes in comparison to HRT cycles alone. Ongoing pregnancy rate (OPR) was higher in HRT plus letrozole group than HRT only group.

Letrozole is a third-generation aromatase inhibitor that leads to mono-ovulatory cycles with short half-life . Miller and his colleagues found that letrozole increased Integrin expression and improved pregnancy and implantation rates among women with endometrial receptivity defects . Another study found that ovarian stimulation with letrozole was associated with increase in the expression of uterine receptivity markers including integrin, leukemia inhibitory factor, and L-selectin.

Eligibility criteria: Inclusion Criteria:

* Women aged between 18 and 37 years with either regular cycles or oligomenorrhoea or amenorrhoea.
* Women undergoing FET cycles.
* Participants should have at least one good-quality blastocyst available for vitrification and also for transfer after warming.
* Participants having optimal endometrium before starting luteal phase support

Exclusion Criteria:

* Women who will refuse to participate in in the study.
* Women who will not reach the optimal endometrium.
* Participants that don't have at least one good-quality blastocyst for transfer after warming.
* PGT embryos will be excluded.

Primary outcomes:
measure: ongoing pregnancy rate (OPR)
timeFrame: 12 weeks
Secondary outcomes:
measure: Clinical pregnancy rate (CPR)
timeFrame: 5 weeks after embryo transfer
measure: Ectopic pregnancy
timeFrame: 7 week
measure: Miscarriage rate
timeFrame: 12 weeks
measure: Implantation rate
timeFrame: 21 days after embryo transfer
measure: live birth rate
timeFrame: 22 completed weeks of gestational age
measure: Number of participants with Hypertensive disorders of pregnancy
timeFrame: 20 weeks gestation till postpartum
measure: Number of participants with Large for gestational age
timeFrame: from gestation till delivery
Other outcomes:
Locations:
city: Zagazig
country: Egypt
facility: Rahem fertility center
Study officials:
affiliation: Rahem Fertility Center
name: Eman El-gindy, MD,PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Elgindy EA, Abdelghany AA, Sibai AbdAlsalam H, Mostafa MI. The novel incorporation of aromatase inhibitor in hormonal replacement therapy cycles: a randomized controlled trial. Reprod Biomed Online. 2022 Apr;44(4):641-649. doi: 10.1016/j.rbmo.2021.10.025. Epub 2021 Dec 20.
citation: Ezoe K, Fukuda J, Takeshima K, Shinohara K, Kato K. Letrozole-induced endometrial preparation improved the pregnancy outcomes after frozen blastocyst transfer compared to the natural cycle: a retrospective cohort study. BMC Pregnancy Childbirth. 2022 Nov 7;22(1):824. doi: 10.1186/s12884-022-05174-0.
citation: An BGL, Chapman M, Tilia L, Venetis C. Is there an optimal window of time for transferring single frozen-thawed euploid blastocysts? A cohort study of 1170 embryo transfers. Hum Reprod. 2022 Nov 24;37(12):2797-2807. doi: 10.1093/humrep/deac227.
citation: Mumusoglu S, Polat M, Ozbek IY, Bozdag G, Papanikolaou EG, Esteves SC, Humaidan P, Yarali H. Preparation of the Endometrium for Frozen Embryo Transfer: A Systematic Review. Front Endocrinol (Lausanne). 2021 Jul 9;12:688237. doi: 10.3389/fendo.2021.688237. eCollection 2021.
citation: Zhang J, Liu H, Wang Y, Mao X, Chen Q, Fan Y, Xiao Y, Kuang Y. Letrozole use during frozen embryo transfer cycles in women with polycystic ovary syndrome. Fertil Steril. 2019 Aug;112(2):371-377. doi: 10.1016/j.fertnstert.2019.04.014. Epub 2019 May 21.
citation: Godiwala P, Makhijani R, Bartolucci A, Grow D, Nulsen J, Benadiva C, Grady J, Engmann L. Pregnancy outcomes after frozen-thawed embryo transfer using letrozole ovulation induction, natural, or programmed cycles. Fertil Steril. 2022 Oct;118(4):690-698. doi: 10.1016/j.fertnstert.2022.06.013. Epub 2022 Jul 19.
citation: Lawrenz B, Melado L, Fatemi HM. Frozen embryo transfers in a natural cycle: how to do it right. Curr Opin Obstet Gynecol. 2023 Jun 1;35(3):224-229. doi: 10.1097/GCO.0000000000000862. Epub 2023 Mar 14.