Effect of low-molecular-weight heparin in women undergoing frozen-thawed embryo transfer cycles: a retrospective cohort study

BMC Pregnancy Childbirth. 2023 May 10;23(1):335. doi: 10.1186/s12884-023-05634-1.

Abstract

Background: Recurrent pregnancy loss (RPL) and recurrent implantation failure (RIF) during in vitro fertilization (IVF) treatment are still tough problems without effective treatments; thus, they are important research topics. There is controversy on whether low molecular weight heparin (LMWH) improves pregnancy outcomes in women with unexplained RPL and RIF. Moreover, currently, there is a paucity of reports on the role of LMWH in the entire population undergoing frozen-thawed embryo transfer (FET) cycles. This study aimed to estimate the effects of LMWH on pregnancy outcomes in women undergoing FET cycles.

Methods: There were 1881 female patients included in the study. Of the 1881 patients, 107 underwent preimplantation genetic diagnosis cycles, which were analyzed individually. The patients were divided into two groups: the LMWH group received injections of 4100 IU/d LMWH from the day of transfer until 14 ± 2 days posttransplant, the control group was the comparison group (without LMWH use). The baseline characteristics and reproductive outcomes of the patients were reviewed.

Results: Of the 1774 women with normal FET cycles, no significant differences were found in the number of embryos implanted (1.31 ± 0.02 vs. 1.28 ± 0.02), embryo implantation rate, biochemical pregnancy rate, clinical pregnancy rate, live birth rate, late abortion rate, and ectopic pregnancy rate between the two groups. The LMWH group had a higher early abortion (17.8% [76/427] vs. 12.5% [55/439], p = 0.030). In the sub-group analysis, among the patients who underwent more than four transfers, the LMWH group had a lower late abortion rate (1.7% [1/60] vs. 13.2% [7/53], p = 0.043). Similarly, of the 107 women who underwent preimplantation genetic diagnosis cycles, the reproductive outcomes were comparable between the two groups.

Conclusion: In the general population and PGD patients, LMWH did not improve pregnancy outcomes. Therefore, the routine use of LMWH is not recommended for early treatment.

Keywords: FET; IVF; Low molecular weight heparin; Recurrent implantation failure; Recurrent pregnancy loss.

MeSH terms

  • Abortion, Habitual*
  • Embryo Implantation
  • Embryo Transfer
  • Female
  • Fertilization in Vitro
  • Heparin, Low-Molecular-Weight* / therapeutic use
  • Humans
  • Pregnancy
  • Pregnancy Rate
  • Retrospective Studies

Substances

  • Heparin, Low-Molecular-Weight