Effect of Low Molecular Weight Heparin in Freeze-thaw Embryo Transfer Cycles in Women With Recurrent Implantation Failure

NCT06991530 — Completed, 392 participants, The Second Hospital of Shandong University

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Registry	NCT06991530
Status	Completed
Study type	Observational
Enrollment	392 (Actual)
Sponsor	The Second Hospital of Shandong University (Other)
Conditions	Low Molecular Weight Heparin, Recurrent Implantation Failure, FET, IVF
Interventions	Low Molecular Weight Heparine (Drug)
Dates	start 2021-01-01, primary completion 2024-11-30, completion 2025-03-01, first posted 2025-05-28, last updated 2025-08-12
Locations	1 site in China

-Summary

Recurrent implantation failure (RIF) is considered a tough problem in assisted reproductive technology (ART) without effective treatments. The effect of low molecular weight heparin (LMWH) in pregnancy outcomes is controversial. In addition, there are few reports on the role of LMWH in population with RIF performing freeze-thaw embryo transfer (FET) cycles. The purpose of this study is to evaluate the effect of LMWH on pregnancy outcomes in women with FET cycles.

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+Arms and interventions

Arm	Type	Interventions	Description
LMWH group		Drug: Low Molecular Weight Heparine	the LMWH group received injections of 4100 IU/d LMWH from the day of transplant
Control group			the control group received the routine luteal support protocol (without LMWH use)

Low Molecular Weight Heparine (Drug): the LMWH group received injections of 4100 IU/d LMWH from the day of transplant

+Outcome measures

Primary outcomes

Ongoing pregnancy rate [from transplantation to delivery (assessed up to 40 weeks of gestation)]: The number of ongoing pregnancies divided by the number of women who received a transfer

Secondary outcomes

biochemical pregnancy rate [from transplantation to delivery (assessed up to 40 weeks of gestation)]: The number of biochemical pregnancy cycles divided by the number of transplantation cycles
clinical pregnancy rate [from transplantation to delivery (assessed up to 40 weeks of gestation)]: The number of clinical pregnancies divided by the number of women who received a transfer
ectopic pregnancy rate [from transplantation to delivery (assessed up to 40 weeks of gestation)]: The number of ectopic pregnancies divided by the number of women who received a transfer
Miscarriage rate [from transplantation to delivery (assessed up to 40 weeks of gestation)]: The number of miscarriages divided by the number of clinical pregnancies

+Eligibility

Sex: Female, ages: 20 Years to 40 Years

Inclusion Criteria:

* Women under or equal to the age of 40 when oocytes were retrieved;
* The history of at least 2 failed fresh embryo transfer/FET cycles and cumulative transfer of ≥ 3 high-quality embryos or cumulative transfer of ≥ 2 blastocysts;
* Planning to FET after IVF or ICSI cycles

Exclusion Criteria:

* Women with untreated hydrosalpinx, uterine cavity occupying lesions (uterine adhesions, submucous fibroids, endometrial polyps, et al.);
* Women with abnormal anatomical structure of uterus (unicornuate uterus, bipedal uterus, et al.);
* Women with endometrial thickness (EMT) < 6mm on the day of transplantation;
* Women or their partner with abnormal chromosome karyotype (not including chromosome polymorphisms);
* Women with the history of recurrent spontaneous abortion (RSA);
* Women with a history of autoimmune or coagulation disorders;
* Women with contraindications to LMWH

+Locations (1)

Facility	City	Country	Status
The Second Hospital of Shandong University	Jinan, Shandong	China