RESUMEN
OBJECTIVE: To investigate an association between polymorphisms related to the implantation process that together could help in the prediction of recurrent implantation failure (RIF). DESIGN: Cohort study. SETTING: Private fertility center and reproductive genetics laboratory. PATIENT(S): Forty-four women presenting RIF, who were included in study group (RIF group), and two control groups, one with 63 women who were attended at our service and became pregnant after the first IVF/intracytoplasmic sperm injection attempt (control group I) and other with 65 fertile women who had at least two children without any treatment and no history of miscarriage (control group II). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Genotyping was performed in the intron region of TP63, VEGFA, MMP2, ESR1, and ESR2 genes and in the 3' untranslated region of the LIF gene on genomic DNA using real-time polymerase chain reaction. RESULT(S): The presence of ESR1/AA (rs12199722) and LIF/GT (rs929271) genotypes was more frequent in the RIF group, leading to a 7.9-fold increase in the chance of women presenting with RIF when compared with women who became pregnant on their first cycle of IVF/intracytoplasmic sperm injection and a 2.8-fold increase when compared with women who became pregnant without treatment. CONCLUSION(S): The association between ESR1 and LIF polymorphisms can help in the prediction of RIF.