Background: The evidence on maternal employment after childbirth and subsequent child mental health is controversial, and maternal employment is often assessed at only one point in time.
Methods: In this prospective birth cohort study analyzing 536 families, we estimated trajectory classes of maternal employment 0-36 months postpartum. We used multivariable linear regression models to examine possible associations between (1) trajectory classes and (2) maternal employment status at 12 months postpartum with child mental health at 4, 5, and 6 years of age.
Results: We identified five different trajectory classes and found substantial adverse associations with later mental health only among boys. For boys, trajectory classes 2 and 3 (characterized by relatively high maternal working hours/week) were associated with worse mental health at ages 5 and 6 compared to class 1 (relatively low or no working hours/week). For girls, in contrast, class 5 (increasing and subsequently decreasing working hours/week) was associated with better mental health compared to class 1. In addition, a positive association between part-time employment at 12 months postpartum and later mental health among boys was found.
Conclusion: Maternal employment may be associated with children's mental health between the ages of 4 and 6, although an appropriate definition of exposure is needed as the time of assessment is important. Whether there are gender differences in the associations of maternal employment with child mental health, or whether this is an issue susceptible to parental perception requires further investigation.