Nonstandard work schedules – shifts that occur outside of traditional daytime hours – are common in the American work force. Recent reports indicate that a fifth of working Americans are engaged in nonstandard shift work  as is at least one adult in a third of dual-earner households (Presser, 2011). Analyses of a cohort of youth aged 14-21 in 1978 found that 9 out of 10 had worked at some type of nonstandard shift by age 39 (Presser, 2011). Despite how common nonstandard employment is, its effects are not fully understood (Presser, 2011).

 Only a few previous studies have examined the impact of nonstandard employment on child obesity, and these studies have arrived at inconsistent findings. Miller and Han (2008) found that either a few years or many years of maternal nonstandard shift work was associated with increased risk of overweight or obesity when children were 13 or 14 years old.  However, Morrissey, Dunifon, & Kalil (2011) found no relationship between maternal shift work and children’s body mass index (BMI). Considering both maternal and paternal shift work, Champion et al. (2012) found that nonstandard employment by fathers alone or by mothers and fathers together was associated with increased odds of overweight or obesity but no association for nonstandard shift work by only mothers.

 Using longitudinal data from the Fragile Families and Child Well-Being Study (FFCWS), this study investigates the impact of both maternal and paternal shift work on child overweight and obesity at ages 3, 5, and 9. It extends previous work in three important ways. First, like (Morrissey et al., 2011) it uses child fixed effects (FE) models, but extends this approach to consider the work schedules of both mothers and fathers. Second, it considers whether associations between parental shift work and overweight and obesity differ for children living with married biological parents, cohabiting biological parents, and single mothers using direct reports on shift work from both mothers and fathers.

 At each time, mothers and fathers were each coded as either unemployed, working only standard shifts, working only nonstandard shifts, or working a mix of standard and non-standard shifts. When appropriate, models included controls for maternal and paternal hours of weekly employment and a number of other family and child characteristics.  In both OLS and FE models, children whose mothers worked a mix of standard and nonstandard shifts had a significantly higher probability of between 0.087 and 0.097 of being overweight or obese compared to those whose mothers worked only standard shifts. This effect was evident and more pronounced in married biological parent families but not in single mother or cohabiting families. Paternal shift work was not consistently related to child overweight or obesity and the inclusion of paternal employment variables did not alter the relationship between the mix of maternal shifts and child obesity. These results suggest the importance of future research on nonstandard employment and of policies and programs that can support families with demanding work schedules.