Does our environment affect our fertility? Some examples to help reframe the question.

The burden of unwanted infertility appears to be increasing, but links to environmental causes have, until recently, been difficult to establish. A large body of data suggests that sperm counts have been declining in Europe and the United States, but interpretation of these statistical trends remains controversial, and the role of the environment uncertain. We were able to show that some currently used pesticides are significantly associated with reduced sperm concentration by linking pesticide concentration in men's urine to results of their semen analysis. In a follow-up study, we showed that prenatal phthalate exposure was linked to subtle differences in genital development of male offspring that could impact the child's future fertility. Researchers are increasingly able to measure levels of environmental chemicals in human samples, and are using these to identify agents that impair fertility. These methods, rather than trend analyses, may lead more directly--and more persuasively--to identifying the role of environment in human fertility.