NIOSH epidemiologic studies of pregnancy outcomes.

The conduct of pregnancy outcome studies among occupationally exposed populations is a relatively new research area with many methodologic and pragmatic difficulties. This paper reviews the experience of conducting reproductive epidemiologic research at the National Institute for Occupational Safety and Health (NIOSH). The advantages and disadvantages of the three epidemiologic study types most often conducted at NIOSH are discussed: 1) surveillance studies, 2) descriptive studies, and 3) industrywide studies. Some of the problems inherent in the conduct of industrywide investigations are illustrated in a discussion of a reproductive outcome study of video display operators currently underway. These problems include sample size, referent availability, exposure and outcome validation, tracing, analytic methods, and cost.