The effect of intralipid on pregnancy rates in in vitro fertilisation (IVF).

OBJECTIVE: Poor uterine receptivity may be one reason for implantation failure in IVF. Some evidence [1-3] suggests an immunological role for reduced uterine receptivity hence many interventions targeted at achieving an 'ideal' immune environment are being investigated. One such therapy, intralipid, has been shown to be effective at suppressing natural kill cell cytotoxicity [4-5] but it remains unclear as to the actual effect in improving pregnancy rates. Thus, the objective of our study was to evaluate the effect of intralipid on chemical pregnancy, clinical pregnancy, live births and clinical pregnancy loss. DESIGN: Retrospective cohort study. MATERIALS AND METHODS: The study evaluated all fresh and frozen embryo transfers (ETs) between 2011 and 2015 (N=29,852) from a multi-site IVF clinic. In patients who had one or more ETs with intralipid, all other ETs were excluded and a randomly selected single ET cycle was chosen for each patient, leaving 11,028 ETs for analysis. This included 545 ETs where intralipid was used and 10,483 control ETs. Intervention and control groups were matched for: year, cycle number, age, number of embryos transferred, number of previous ETs without a live birth, and use of adjuvant therapies. Univariate comparison of proportions was performed using the Chi square test, while Mann Whitney U testing was used for univariate comparison of continuous variables. Logistic regression was used to allow for potential confounding variables. Analysis was performed initially on the full cohort and then on matched cases and controls. RESULT(S): Analysis of the full cohort demonstrated reduced rates for the intralipid group of chemical pregnancy (crude OR 0.61 CI 0.50-0.70), clinical pregnancy (crude OR 0.58 CI 0.48-0.71) and live birth (crude OR 0.52 CI 0.42-0.65). Once confounding factors had been allowed for through logistic regression (adjusted ORs) no statistically significant differences were seen between ET cycles with or without intralipid.