The most convincing identification strategy for estimating long-term health consequences of
adverse conditions in utero and poor fetal health requires variation in early health conditions
that is not confounded by other factors, such as childhood socioeconomic conditions and
family background, that might also affect adult health outcomes. A methodological strength
of the empirical approach is the model’s inclusion of an extensive array of well-measured
dimensions of childhood family and neighborhood background. The unusually rich set of
family and child-specific control variables included in the models reduced potential omitted
variable bias, providing stronger evidence on whether the estimated effects of low birth
weight and childhood socioeconomic disadvantage on disease onset in adulthood were
causal. In addition, the socioeconomic factors in this study were measured more accurately
and comprehensively than in other surveys used to examine the impact of childhood factors
on health in adulthood because the assessment of these factors has been a primary focus of
the PSID