Background: The relative income hypothesis states that one's income in comparison to others can affect one's mental health. Also, greater social support from family and friends can be beneficial for mental health. Agent-based modelling (ABM), which is a simulation modeling technique, can be used to explore the complex effects of income inequality and social factors on mental health.

Methods: Data came from the All Our Families study, a community-based, longitudinal cohort from Calgary, Canada. ABM was then used to simulate various methods of reducing inequality and to examine their effects on reducing the likelihood of depression. Increasing minimum wage, the Canada Child Benefit (CCB), the Alberta Child Benefit (ACB), and the Ontario Universal Basic Income (ON UBI) were tested. In addition, agents were able to make decisions about expanding or reducing their social network.

Results: The number of people a mother has for social support (OR=0.91, 95% CI=0.87-0.94), was associated with a reduced likelihood of depression. For relative income, every $10 000 income category decrease with respect to the perceived income category of other households in a mother’s neighbourhood resulted in a 12% increase in the probability of a mother being depressed. Increasing income through increasing minimum wage (OR=0.96, 95% CI=0.91-1.00), the CCB (OR=0.93, 95% CI=0.88-0.97), and the ON UBI (OR=0.92, 95% CI=0.87-0.96) were all associated with a decrease in probability of being depressed.

Conclusions: Reducing inequality through increasing minimum wage, or other government transfer programs, and increasing social support can significantly reduce the probability of expectant mothers being depressed.