The purpose of this study was to assess whether labor and delivery events were risk factors for sudden infant death syndrome (SIDS). A nested case-control design was used. From the 1974 cohort of live births for Upstate New York (exclusive of New York City), resident mothers (n = 132,948), SIDS cases, and living controls were selected. Data were abstracted from hospital delivery and vital records for 148 autopsied cases and 355 frequency-matched controls. With the use of unconditional logistic regression, no increase in SIDS risk was observed for artificial rupture of membranes, medication use during labor, induction/augmentation of labor, or anesthesia for delivery. An increased risk of SIDS was observed for labor 16 hours or more (odds ratio (OR) = 2.6, 95% confidence interval (CI) 1.1-6.5) and vaginal breech delivery (OR = 7.2, 95% CI 0.7-72.2). Significant inverse trends were observed for Apgar scores and risk of SIDS.