Potential implications of missing income data in population-based surveys: an example from a postpartum survey in California.

Objectives: Income data are often missing for substantial proportions of survey participants and these records are often dropped from analyses. To explore the implications of excluding records with missing income, we examined characteristics of survey participants with and without income information.

Methods: Using statewide population-based postpartum survey data from the California Maternal and Infant Health Assessment, we compared the age, education, parity, marital status, timely prenatal care initiation, and neighborhood poverty characteristics of women with and without reported income data, overall, and by race/ethnicity/nativity.