Smooth fit of the joint associations of the log-transformed dioxin and PCB mixture with infant neurodevelopment at 6 months using quantile g-computation for (a) MDI and (b) PDI in the Hokkaido Study Small Cohort of the Hokkaido Study on Environment and Children’s Health (n = 259). Models were adjusted for maternal age, education, household income, work status during pregnancy, smoking status during pregnancy, and fish intake during pregnancy (inshore and deep-sea fish).