This analysis suggests that although few of the deleterious consequences of maternal employment observed around the time of school entry persist through early adolescence for the typical child, there appear to be sharp socioeconomic variations in these small average effects, with much more negative impacts predicted for advantaged youths. Moreover, it provides evidence that work during the earliest (rather than later) years of the child’s life may be associated with particularly deleterious consequences for cognitive development but not necessarily other outcomes. For instance, maternal employment after the third year of the child’s life is most strongly associated with obesity among advantaged youths.
The most favorable results for low SES 10 and 11 year olds are predicted when the mother works approximately half-time – averaging 20 hours per week is anticipated to raise verbal, mathematics and reading test scores by 0.22, 0.15 and 0.17 standard deviations, compared to no work, with little effect on excess body weight. Forty hours of weekly employment, which is rare, appears to eliminate many of the cognitive benefits but still to leave the disadvantaged adolescents better off than if the mother did not hold a job.
By contrast, the estimates suggest substantial and uniformly negative consequences of maternal employment for high SES youths. Averaging 40 hours per week decreases expected cognitive test performance by.14 to.20 standard deviations and raises obesity (overweight risk) by 7.3 (15.2) percentage points. We do not fully understand why maternal job-holding is particularly deleterious for high SES youths. A tentative conclusion, however, is that much of the cognitive impact occurs because employment pulls these children out of home environments conducive to learning. This does not explain the findings for obesity, but there is some suggestion of a role for determinants of weight common to both the child and mother.
These findings demonstrate that the pathways to desirable child outcomes probably vary with family circumstances and highlight the need to examine other potential sources of SES disparities. For example, disadvantaged children are often cared for by grandparents (Anderson and Levine, 2000; Rosenbaum and Ruhm, forthcoming), which might reduce the negative effects of maternal employment if relatives provide time investments of similar quality as mothers. Alternatively, labor supply by high SES women might relatively frequently be motivated by divorce or other family events that adversely affect children. Also, experimental evidence indicates that the work requirements of welfare reform harm adolescent school performance (Gennetian et al., 2002
), suggesting different consequences of voluntary and mandated maternal employment for low SES youths.
Over 90% of mothers work during their child’s first 10 or 11 years but fewer than half average 20 or more hours and less than 6% at least 40 hours weekly. When combined with the results above, this suggests that low SES families are generally making employment decisions consistent with the most favorable child outcomes. Conversely, even limited employment is predicted to have negative effects for advantaged adolescents.
High SES youths, however, do relatively well, however, even when their mothers work. shows the outcomes predicted at 0, 20 and 40 hours of maternal employment.46
An advantaged 10 or 11 year old whose mother averaged 40 hours per week is expected to have considerably worse cognitive performance than if her mother did not work – scoring at the 52nd
percentiles on the three tests, rather than the 57th
percentiles. Nevertheless, this is well above the 33rd
percentiles predicted for a low SES child whose mother averaged 20 hours per week (approximately where test performance is maximized). Overweight risk and obesity are also relatively rare for advantaged youths, unless their mothers were employed full-time. The welfare implications of these findings are unclear since child outcomes are just one argument in the parents’ utility function.47
High SES families may willingly forgo some gains to their children to obtain other benefits.48
Alternatively, they might be unaware of the negative labor supply effects, implying suboptimal outcomes.
Predicted Test Scores and Obesity/Overweight Prevalence by Maternal Employment and SES
Several limitations of the analysis deserve mention. The NLSY is not entirely representative, since it excludes some fertility of older mothers and is restricted to children born between 1979 and 1988. The employment consequences may depend on the technologies or institutional arrangements in place, and so could differ across locations or for more recent cohorts (e.g. if workplaces have become more “family-friendly”). Better understanding the mechanisms by which parental investments promote child development might facilitate less costly methods of achieving the same benefits. The role of paternal employment also needs to be more carefully examined, which is difficult given the shortcomings of existing data sources.
The models rely on the explanatory variables to account for the selection into market work, rather than exploiting exogenous sources of variation. Identifying natural experiments or instrumental variable approaches would be helpful. That said, the negative consequences of maternal employment for high SES youths are unlikely to be an artifact of the estimation technique. The predicted labor supply effects typically become less favorable with more complete controls for heterogeneity and women tend to work less if their offspring have low test scores in previous years, probably inducing a positive correlation between employment and cognitive development. Maternal fixed-effect and propensity score models also yield similar or more negative estimates than corresponding OLS specifications for advantaged adolescents. On the other hand, reverse causation may be more important for disadvantaged youths, suggesting that the preceding estimates may overstate the benefits of maternal employment for them.