Developmental health is governed by biology and the societal culture that shapes family planning. This context should not be ignored in epidemiologic studies that address the effect of parental exposure from environmental and occupational agents on prenatal development, growth and survival, on adverse birth effects, or on postnatal events. It is important to have a thorough basic knowledge of developmental health in the population under study and to consider this basis in study design and performance. One way of accomplishing this task is to combine strengths of population-based cohort studies and nested case-control studies. Sibship-based cohorts and case-control studies that make use of biomarkers may provide particular advantages. Future research on the impact of parental exposure should be more strongly based on biological knowledge about the genetic, immune, and endocrine regulation of prenatal growth and development.