Thanks Emily! I love Nick's comments about the contextual factors related to economics, etc. that influence family planning. I know you know I am interested in the social communication/messaging piece you bring up. There was literature in the 1990s in developing countries, published by one of the collaborators on the project you are analyzing, that showed that contraceptive use was influenced by the use of contraceptives by other people in your network, measured as a contextual variable.
For how to model SES, I just want to make sure that you got that the options include as a "confounder" - although your use of them term "covariate" is more appropriate, effect modifier, and mediator. In addition, contextual SES factors can be considered.