['To determine whether ovarian follicular fluid (FF) stem cell factor concentrations are associated with successful IVF pregnancies.', 'Nested case-control design evaluation of stem cell factor levels from the FF of oocytes fertilized and transferred after controlled ovarian hyperstimulation.', 'University-based ART program.', 'Infertile women undergoing IVF in a university-based ART program.', "Fifty-seven FF samples from a cohort of patients (n = 13) with tubal factor and unexplained infertility were stored at -80 degrees C and subsequently evaluated for stem cell factor concentration. Patients with endometriosis, polycystic ovary disease, and male factor infertility were excluded. Stem cell factor concentrations were measured using a commercially available ELISA kit according to the manufacturer's specifications. The groups were analyzed using a one-way analysis of variance, and significance was determined using the chi2 analysis of contingency table, the unpaired t-test, or the Mann-Whitney rank-sum test.", 'FF stem cell factor concentration, pregnancy.', 'Stem cell factor concentrations were significantly higher in the FF of the patients who achieved successful pregnancies than in those who did not (641.7+/-75.2 pg/mL versus 475.5+/-50.58 pg/mL).'] Are elevated ovarian follicular fluid stem cell factor concentrations associated with improved pregnancy rates in in-vitro fertilization cycles?