Low-Molecular-Weight Heparin (LMWH) in Women with Repeated Implantation Failure

Low-molecular-weight heparin in thrombophilic women receiving in vitro fertilization/intracytoplasmic sperm injection: A meta-analysis

INTRODUCTION

This meta-analysis aimed to evaluate the efficacy and safety of low-molecular-weight heparin (LMWH) on pregnancy outcomes in thrombophilic women receiving in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI).

MATERIAL AND METHODS

A systematic literature search of PubMed, EMBASE, the Cochrane Library, and China National Knowledge Infrastructure was performed to identify randomized controlled trials (RCTs) comparing LMWH with no treatment or placebo published from database inception until February 19, 2023. Primary outcomes were the clinical pregnancy rate and implantation rate, and secondary outcomes were the live birth rate, miscarriage rate, and the risk of bleeding events. The certainty of the evidence was rated using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) system. Meta-analysis was conducted using STATA 14.0.

RESULTS

Five RCTs involving 1094 thrombophilic women receiving IVF/ICSI were finally included. Administration of LMWH was associated with statistically higher clinical pregnancy rate (4 RCTs, risk ratio [RR] 1.50, 95% confidence interval [CI] 1.23-1.82, p < 0.001, low certainty evidence), implantation rate (5 RCTs, RR 1.49, 95% CI 1.25-1.78, p < 0.001, very low certainty evidence), and live birth rate (2 RCTs, RR 2.15, 95% CI 1.60-2.89, p < 0.001, very low certainty evidence), but with statistically lower miscarriage rate (2 RCTs, RR 0.36, 95% CI 0.15-0.86, p = 0.021, very low certainty evidence). However, using LMWH was linked to a higher risk of bleeding events (2 RCTs, RR 2.36, 95% CI 1.49-3.74, p < 0.001, very low certainty evidence).

CONCLUSIONS

Very low certainty evidence suggests that administration of LMWH may benefit pregnancy outcomes in thrombophilic women receiving IVF/ICSI treatment, although it may also increase the risk of bleeding events. However, before putting our findings into practice, healthcare professionals should conduct an in-depth evaluation of the available evidence and specific patient situations. Furthermore, due to the low methodological quality of the included studies, more high-quality studies are needed to validate our findings in the future.

Effect of a 20% intravenous fat emulsion therapy on pregnancy outcomes in women with RPL or RIF undergoing IVF/ICSI: a systematic review and meta-analysis

Background and Aim

The aim of this study was to evaluate the efficacy a 20% intravenous fat emulsion therapy in women suffering from recurrent pregnancy loss or recurrent implantation failure (RPL/RIF) who are undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).

Materials and Methods

We searched Cochrane Library, ISI Web of Science, MEDLINE, ClinicalTrials.gov, PubMed, and Scopus using relevant keywords during February 2020 for randomized controlled trials (RCTs) comparing the therapy versus placebo or no intervention in women suffering from RPL/RIF and undergoing IVF/ICSI.

Results

We included five RCTs with 840 patients. The intravenous fat emulsion therapy was significantly effective in increasing clinical pregnancy rates compared to the control group (risk ratios [RR] = 1.48, 95% confidence intervals [CI] [1.23, 1.79], P < 0.001). Furthermore, ongoing pregnancy and live birth rates were significantly higher with 20% intravenous fat emulsion therapy RR = 1.71, 95% CI [1.27, 2.32], P = 0.005 and RR = 1.85, 95% CI [1.44, 2.38], P < 0.001. Despite the statistically significant differences, the quality of evidence was only considered moderate, and this was primarily due to high risk of bias in the included RCTs.

Conclusion

Our review provides a moderate level of evidence that intravenous fat emulsion therapy is effective in improving reproductive outcomes among women with RPL/RIF performing IVF/ICSI techniques. Further, investigation is required to ascertain optimal dosage and timing of administration.

Relevance for Patients

Women suffering from RPL or RIF may wish to consider discussing with their reproductive endocrinologist the addition of a 20% fat emulsion therapy to planned IVF or ICSI cycles, which may improve outcomes.

In vitro Fertilization Procedures with Embryo Transfer and Their Association with Thrombophilia, Thrombosis and Early Antithrombotic Treatments

In vitro fertilization (IVF) procedures have been frequently associated with antithrombotic treatments, in particular, to aspirin or low-molecular-weight heparin (LMWH). The rationale of this treatment is based on the increase of thrombotic risk occurring in this clinical context. Indeed, both prothrombotic changes of coagulation parameters specifically related to IVF procedures as well as the presence of potential thrombophilic alterations may concur to increase the risk in these women. Furthermore, the presence of thrombophilia has been suggested as a potential cause of recurrent IVF failures. Therefore, antithrombotic treatments have been historically planned to prevent thrombotic disorders during pharmacological ovarian stimulation and/or to increase a successful rate of pregnancy and live births after IVF with embryo transfer. However, up to date, the role of inherited and\or acquired thrombophilia is still debated as well as a univocal therapeutic approach is lacking in women with infertility. The administration of antithrombotic drugs differs in several studies and even the dosages of aspirin and\or low-molecular-weight heparin are different. This review focuses on underlining current evidence on the role of thrombophilia and thromboprophylaxis in women selected for IVF with embryo transfer.

Pregnancy-Related Venous Thromboembolism

Pregnancy is associated with an increased risk of venous thromboembolism (VTE), with a reported incidence ranging from 0.49 to 2 events per 1000 deliveries. Risk factors include advanced maternal age, obesity, smoking, and cesarian section. Women with a history of previous VTE are at a 4-fold higher risk of recurrent thromboembolic events during subsequent pregnancies. Additionally, the presence of concomitant thrombophilia, particularly factor V Leiden (homozygosity), prothrombin gene mutation (homozygosity), or antiphospholipid syndrome (APS), increases the risk of pregnancy-related VTE. Low-molecular-weight heparin (LMWH) and unfractionated heparin (UFH) are the drugs of choice for anticoagulation during pregnancy. LMWH is preferred due to ease of use and lower rates of adverse events. Women with high thromboembolic risk particularly those with a family history of VTE should receive antepartum thromboprophylaxis. Women with low thromboembolic risk or previous VTE caused by a transient risk factor (ie, provoked), who have no family history of VTE, may undergo antepartum surveillance. Postpartum anticoagulation can be considered in women with both high and low thromboembolic risk.