Epidemiologic evidence on biological and environmental male factors in embryonic loss.

Epidemiological studies on male mediated developmental toxicity may focus on links between environmental exposure of the male and pregnancy failures or disorders in the offspring. Alternatively, the focus may be on biological markers of male fecundity and developmental disorders. The study design only rarely allows for a combination of these two approaches. Demonstration of effects of male exposure on the male reproductive system, and subsequent demonstration of links between observed abnormalities of the male system with abnormalities of foetal and childhood development in the offspring would provide strong evidence for causal associations between exposure and outcomes.