Little is known about how birth outcomes vary in rural areas by degree of rural isolation. We conducted a retrospective cohort study of all births in Quebec, 1991-2000 to assess birth outcomes by the degree of rural isolation according to metropolitan influence as measured by work force commuting flows between rural and urban areas. Compared with urban areas, crude risks of preterm birth, small-for-gestational age birth, stillbirth, neonatal death and postneonatal death were similar in rural areas with strong metropolitan influence, but were significantly higher for preterm birth, stillbirth and postneonatal death in rural areas with weak or no metropolitan influence, and for neonatal death in rural areas with no metropolitan influence. Adjustment for maternal characteristics (age, mother tongue, education, marital status, parity, plurality and infant sex) attenuated the associations. The adjusted odds ratios [95% confidence intervals] were 1.36 [1.12, 1.64] for stillbirth in rural areas with weak metropolitan influence, 1.63 [1.14, 2.32] for neonatal death in rural areas with no metropolitan influence, 1.78 [1.21, 2.63] and 1.37 [1.07, 1.75] for postneonatal death in rural areas with weak and no metropolitan influence, respectively. Much higher neonatal death rates were observed for preterm or low-birthweight babies in rural areas with no metropolitan influence, suggesting inadequate access to optimal neonatal care. We conclude that birth outcomes in rural areas differ according to the degree of rural isolation. Fetuses and infants of mothers from rural areas with weak or no metropolitan influence are particularly vulnerable to the risks of death during the perinatal and postnatal periods.