Fig. 2.

Schematic illustration of selection in utero and fetal origins “damage” in response to a stressful environment. The solid curve shows the frequency distribution of fetal survivability in an average ambient environment. The vertical solid line represents the criterion below which a mother spontaneously terminates the pregnancy. An elevated stress-level environment, in which the maternal capacity to invest declines and the criterion for termination therefore shifts right, would increase selection in utero. Alternatively, in an elevated stress environment; the survivability distribution for fetuses may shift left, resulting in the dashed-line frequency distribution and cohort “damage” among the surviving births. In response to population stressors, both selection and damage in utero may occur but at different quantiles of the survivability distribution. In addition, the maternal criterion for spontaneous termination likely varies across the population, which suggests that selection and damage may be observed in the same conception cohorts.