Iron consumption among mothers has recently been found to decrease the risk of autism in offspring. However, epidemiological evidence of an increasing iron deficiency among mothers or infants is lacking, and evidence within an individual-level framework of iron deficiency confers doubt upon iron's role as a direct cause of autism. We attempt to review the evidence that challenges a direct causal explanation of in utero or infancy iron deficiency leading to autism and, instead, reveal iron to be more likely an effect modifier for another, yet unknown, cause of autism.