Abstract
Study question
What is the effectiveness of IV Intralipid (IVI) in improving pregnancy rates in women undergoing IVF with history of Recurrent implantation failure (RIF) to improve reproductive outcomes.
Summary answer
The evidence to support the use of IVI at the time of embryo transfer in women with RIF is limited. More RCTs are needed. What is known already: Optimising the implantation process following embryo transfer remains a clinical challenge with 10% of couples undergoing IVF affected by (RIF). Immunotherapy could help to optimise endometrial receptivity and increase the chances for successful conception in women with history of RIF. Intra-venous Intralipid (IVI), a fat-based emulsion of soybean oil, glycerine, phospholipids, egg, and polyunsaturated fatty acids, has been evaluated in several trials as a potential intervention to downregulate the uNK cells and macrophages as well as inhibit the pro-inflammatory mediators including T1 helper cells. Evidence synthesis is needed to evaluate the effectiveness of this intervention.
Study design, size, duration
We performed this systematic review using a prospectively registered protocol (CRD42019148517) and reported in accordance with the PRISMA guidelines. Participants/materials, setting, methods: We searched MEDLINE, EMBASE and CENTRAL for any randomised trials evaluating the use of IVI at the time of embryo transfer in women undergoing assisted conception until September 2020. We extracted data in duplicate and assessed risk of bias using the Cochrane Risk of Bias tools. We meta-analysed data using a random effect model and reported on dichotomous outcomes using risk ratio (RR) and 95% confidence interval (CI).
Main results and the role of chance
We included five randomised trials reporting on 843 women with an overall moderate risk of bias. All trials used 20% IVI solution at the time of embryo transfer compared to normal saline infusion or no intervention (routine care). The IVI group had a higher chance of clinical pregnancy (172 vs 119, RR 1.55, 95%CI 1.16–2.07, I2 44.2%) and live birth (132 vs 73, RR 1.83, 95%CI 1.42–2.35, I2 0%) post treatment compared to no intervention.
Limitations, reasons for caution
Our findings are limited by the small sample size and the variations in treatment protocols and population characteristics.
Wider implications of the findings: Our meta-analysis offers an overview on the value of IVI to help women affected by RIF. Given the limitations and the quality of included trials, adopting the use of IVI a-la-carte to couples undergoing IVF remains immature. IVI should not be offered until larger RCTs demonstrate a persistent benefit.
Trial registration number
CRD42019148517
Adjunct low-molecular-weight heparin to improve live birth rate after recurrent implantation failure: a systematic review and meta-analysis
