Administration of low-molecular-weight heparin in patients with two or more unsuccessful IVF/ICSI cycles: a multicenter cohort study.

To compare the effects of the administration of low-molecular-weight heparin (LMWH) in subfertile patients with two or more unsuccessful IVF/ICSI cycles. In this six-center two-arm retrospective cohort study, the study population (230 women) underwent a GnRH-antagonist protocol and was classified into two groups, according to the couse of LMWH or not. Groups were compared regarding the clinical and IVF/ICSI cycle characteristics and reproductive outcomes, whereas clinical pregnancy and miscarriage constituted the primary endpoints. Logistic regression analysis was performed to determine the potential predictors of clinical pregnancy, miscarriage and live birth rates using the Enter method. Baseline characteristics were comparable in the two groups. There was no statistically significant difference between the two study groups with regard neither to clinical pregnancy and miscarriage rates (33/133 vs. 20/97, p = .456 and 15/133 vs. 9/97, p = .624, respectively), nor to the secondary outcomes preset for this study (all p values >.05). Logistic regression revealed that age of the woman and ICSI and dose of gonadotrophins used were predictors of clinical pregnancy and live birth, respectively. In conclusion, there is no evidence to support the standard addition of LMWH in patients with two or more unsuccessful IVF/ICSI cycles.