Note. The panels present the magnitude of the associations (in Hazard Ratios) between gestational age (measured in weeks and centered at 40 weeks of gestation) and Autism (Panel A), Psychotic or Bipolar Disorder (Panel B), and Suicide Attempt (Panel C). The lines represent the best fitting quadratic models. The Baseline Model (the solid black line) compares unrelated individuals in the entire population. The Adjusted Model (the dotted black line) compares unrelated individuals in the population while also controlling for measured covariates, such as maternal and paternal age at childbearing, highest level of education, and psychiatric problems. The Fixed Effects Model (the dotted blue line, with the 95% confidence intervals represented in the shaded blue areas) presents the associations when comparing differentially exposed siblings and controlling for the measured covariates. The dotted blue line, therefore, presents the magnitude of the association that is independent of genetic and environmental factors shared by siblings, as well as the measured covariates. For more details about the results, see D’Onofrio et al., (2013).