Table 2.

Description of mediation effects

Effect Measure	Description
Total Effect	The overall effect of the exposure on an outcome: --For the difference method, this is the regression output for the exposure when not adjusted for the mediator. --For product of coefficients, this is the sum of direct and indirect effect
Direct Effect	The effect of the exposure on an outcome when the intermediate variable is removed
Indirect Effect	The effect of the exposure on an outcome through an intermediate variable
Proportion Eliminated	How much of the total effect would be removed through action on the intermediate variable (setting the mediator to the same level for all pregnant women) [26]: --For the difference method, this is the difference between the total effect and regression output for the mediator-adjusted regression, divided by total effect (minus one if using exponentiated outputs) --For product of coefficients, this is the indirect effect divided by total effect [14]