Social Causation, Health Selection, and First-Time Mothers Work Two Years after Birth

Several factors shape if and when new mothers return to work following birth. The health status of the new child has been an understudied dimension of mothers returning to work. Social causation theories suggest economic hardship from structural inequalities lead to poorer health and perpetuated poverty (Rothwell et al., 2019; Delobel-Ayoub et al., 2015). Conversely, health selection theories propose that poor health precipitates greater socioeconomic challenges (Kröger et al., 2015). Caring for a child with health challenges involves significant financial and time costs, affecting maternal employment during early childhood (Stabile & Allin, 2012).

We aim to disentangle the factors driving mothers’ return to work by systematically testing social causation and health selection theories with the following questions:

1. How often do first-time mothers return to work following birth and to what extent is work associated with pre-existing social disadvantage (social causation)?
2. To what extent are returns to work explained by poor infant health (health selection)?

Methods

We used Oregon administrative data from health, employment, and social service agencies for first-time births in 2016 and 2017. Birth records were linked to employment for 8 quarters before and after birth (2014 to 2019). A total of 17% of first-time mothers (n=5,733) were dropped because they had no earnings across the entire study period, resulting in an analytical sample of n=27,632. The dependent variable was work two years after birth (full-time as approximately 35 hours per week; part-time was work less than 35 hours per week). Social causation factors included: (1) maternal education level at birth, (2) employment prior to birth, and (3) Medicaid and WIC participation at birth. Poor infant health was measured as low birth weight or child receiving care in the Neonatal Intensive Care Unit (NICU). Descriptive, bivariate, and multivariate regression models were tested. Interactions between social causation and health selection tested the extent to which poor infant health moderated the social causation influences.

Results

At two years post birth, 42% of mothers worked part-time and 20% worked full-time. Around 70% of mothers who were working before birth had returned to work 2 years postnatal. For social causation, pre-birth employment, mother’s education, and Medicaid at birth were the strongest predictors of post-birth employment. Poor infant health (health selection) also reduced the likelihood of any work and part-time work at 2 years but was unrelated to full-time work and returns to work. Interactions between social causation and health selection were evident: e.g., for both mothers without prenatal work history and mothers on Medicaid, poor infant health was associated with a 6-percentage point (p < .001) reduction in the likelihood of working after birth.

Discussion

Both pre-existing socio-economic position and infant health influence mothers’ post-natal work patterns. However, we find greater support for the social causation framework. Further, poor infant health is especially detrimental for low-income families with less connection to the labor market pre-birth. These patterns illuminate a need for new and complementary policies that target the economic and caregiving needs of low-income families whose children experience health challenges.