PURPOSE: Environmental influences on reproductive success are recognized. We hypothesized that location of fertility clinics may influence treatment success and explored this hypothesis utilizing donor egg IVF (IVF) embryo transfer (ET) model. METHODS: Publicly accessible national registry data (Society for Assisted Reproductive Technology) on fresh & frozen (FET) ET cycles undertaken at participating clinics across North America (n = 444 IVF centers) for 2007 were utilized. Information on number of donor egg IVF cycles, live birth (LB) rate following fresh and frozen ET(FET), average number (#) of ET and IVF center's location, geographical coordinates (latitude, longitude, altitude), annualized average temperatures and midyear regional ultraviolet B (UVB) radiation intensity were obtained. Multivariable logistic regression analyses assessed relationship between LBR (in tertile and uppermost versus lesser quartiles) following fresh and FET with geographical coordinates (region and altitude of clinic location) and ecological influences (average temperature and midyear UVB intensity), adjusting for #ET and clinic experience with donor egg IVF. RESULTS: Average number of fresh ET, clinic location (region) and midyear UVB intensity were positive predictors of LBR following fresh ET, whereas altitude and annualized average regional temperature demonstrated an inverse relationship with LBR following fresh ET. For FET cycles, #ET, clinic region and altitude were positive determinants of increasing LBR's. Annualized regional temperature and midyear UVB failed to demonstrate any relationship with LB following donor egg FET. CONCLUSION: Our data suggest that ecological influences may relate to donor egg IVF cycle success. Future studies are needed to better elucidate the mechanisms that could explain the observed associations.