Does the length of maternity leave affect maternal health?

• Author: Chatterji, Pinka

1. Introduction

   In the United States, 51% of mothers of infants currently work outside the home (Bureau of Labor Statistics 2003). Among mothers who return to work during the first year after childbirth, almost all return to work by the third month (Klerman and Leibowitz 1994; Cantor et al. 2001). The large number of infants with employed mothers has led to an increased interest in the effects of maternal employment during infancy on child health and development. Recent studies suggest that some forms of maternal employment during the child's first year are detrimental to children's cognitive development and lead to more behavioral problems (Blau and Grossberg 1992; BrooksGunn, Han, and Waldfogel, 2002; Waldfogel, Han, and Brooks-Gunn 2002; Baum 2003). These studies imply that longer maternal leaves will benefit children.

   Previous research, however, does not consider that in addition to improving children's health and development, longer maternity leaves also may affect the health and well-being of mothers. A few correlational studies in the public health literature show that women who are employed postpartum or who return to work soon after childbirth experience more mental and physical health symptoms than other women (Gjerdingen et al. 1993, 1995; Hyde et al. 1995), perhaps because of increased stress and obligations. While the detrimental effects of physical and mental health problems to the mother are obvious, these conditions also may affect the child and other family members through emotional and financial distress. We know very little about this aspect of maternal employment despite the large number of women in the United States who currently balance a job outside the home with the care of a young infant (Hyde 1995).

   From a policy perspective, it is useful to consider the effect of maternity leave length on both mothers and children. Concerns about the health of infants and postpartum women were motivating forces behind the Family and Medical Leave Act (FMLA) of 1993. The case for longer leaves is bolstered if longer leaves benefit mothers as well as children. In the case that longer leaves have neutral or detrimental effects on maternal health, this information still is needed to inform the debate over family leave policy. To date, however, despite a number of recent studies on maternal employment and child health, there is little empirical evidence regarding whether longer maternity leave affects maternal health (Hyde 1995). This evidence is still needed today despite the passage of the FMLA because states currently are passing or are considering legislation that would provide paid family leave. This policy change would likely increase the length of maternity leave but at a cost to states, employees, and businesses. Without information about the health impact of longer maternal leave after childbirth, it is difficult to weigh the costs and benefits of these proposed state-level policy changes.

   This paper investigates how the length of maternity leave affects maternal health in a sample of mothers who returned to work after childbirth. Data come from the National Maternal and Infant Health Survey (NMIHS) of 1988. This survey is particularly useful because it was conducted before the FMLA was enacted in 1993, allowing us to use empirical methods that take advantage of pre-FMLA variation in maternal leave policies across states. Maternal health is represented by three measures. As discussed further here, the first two examine depressive symptoms using the Center for Epidemiological Studies Depression (CES-D) Scale, a widely used screening tool for depression. The third measure of maternal health represents overall health and is a dummy variable indicating whether the mother had at least three outpatient visits for any health problems (mental or physical) during the first six months after childbirth. We estimate baseline models using ordinary least squares (OLS) methods and then address the potential endogeneity of the return-to-work decision using instrumental variables (IV) methods.

   The results indicate that among employed mothers of infants, delaying the return to work decreases the number of depressive symptoms. Holding other factors constant, a one-week increase in the length of maternal leave from work would reduce a scale of depressive symptoms on average by 6-7%; however, it is not clear whether this reduction has clinical significance because we find only weak evidence that the length of maternity leave is significantly associated with a reduction in the probability of meeting a threshold of depressive symptoms that is indicative of clinical depression. We also find a negative but statistically insignificant association between the length of maternal leave and having had at least three postpartum outpatient visits for mental or physical health problems. These findings contribute to the growing literature on maternal leave policy, which focuses primarily on the benefits of leave for child health and development, by evaluating the influence of longer maternal leave on the health of mothers.

2. Returning to Work and Maternal Health

   To the best of our knowledge, no previous study in the economics literature has explored the effect of the length of maternity leave on maternal well-being. In the economics literature, most of the research on maternal leave has focused on the impact of leave and leave policies on labor market outcomes, such as employment, wages and job continuity (Waldfogel 1998; Klerman and Leibowitz 1999), and child health and development (Winegarden and Bracy 1995; Ruhm 2000; Baum 2003). These latter studies suggest that longer maternity leave has positive effects on children's physical health (proxied by mortality) and cognitive development.

   Winegarden and Bracy (1995) and Ruhm (2000) use time-series data from European countries to study the effect of paid maternal leave on child health. Both Winegarden and Bracy and Ruhm find that longer paid leave is associated with reductions in infant mortality; Ruhm additionally finds that longer maternal leave is associated with lower rates of young child mortality. Baum (2003), using data from the National Longitudinal Survey of Youth, demonstrates that returning to work within the first three months of life is associated with lower cognitive test scores during childhood. These studies suggest that longer maternal leave after childbirth may benefit child health and development.

   A few studies from other disciplines have explored the impact of returning to work on the mother's health. In regard to physical health, employed postpartum women have higher rates of respiratory infections, breast symptoms, and gynecologic problems compared to postpartum women who are not employed (Gjerdingen et al. 1993, 1995). This research on physical health is based on a sample of 436 first-time mothers in Minnesota. In regard to mental health, there is some mixed evidence that among employed mothers, returning to work earlier increases depressive symptoms. Hyde et al. (1995), for example, uses a sample of 570 mostly white mothers in Wisconsin to explore the postpartum employment experience. They find that among mothers who are back at work four months postpartum, a short length of maternal leave increases the probability of depression but only among mothers who also have marital concerns and mothers who feel their jobs are unrewarding. Gjerdingen and Chaloner (1994), based on a sample of 436 married, employed, first-time mothers in Minnesota, find that returning to work within 24 weeks alter childbirth, as well as longer work hours, is associated with poor mental health. These studies are based on small, nonrepresentative samples. Moreover, it is not clear whether the association between shorter maternity leave and increased depressive symptoms is causal.

   McGovern et al. (1997) address some of these problems by accounting for the possibility that the timing of the return-to-work decision is endogenous. They find that maternity leave length has a positive effect on a mother's well-being, measured at about seven months postpartum using a generic measure of mental health, vitality, and role function. As identifying instruments, these researchers use a set of variables that measure the infant's health endowment (birth weight and gestation, congenital anomalies), the infant's race, health insurance, maternal leave policies, child care arrangements, and job characteristics. These variables are shown in the analysis to be reasonably adequate predictors of maternal leave length. However, it seems unlikely that they can be validly left out of the maternal health equation. For example, there is evidence from other studies that infant health and child care arrangements affect maternal stress and depression (Gjerdingen et al. 1995; Mandl et al. 1999: McLennan, Kotelchuck, and Cho 2001). No results from overidentification tests are shown to justify these exclusions.

   The present study addresses the endogeneity problem with a different set of instruments. We use state-level labor market conditions and state-level maternal leave policies as identifying instruments rather than the potentially endogenous individual characteristics used by McGovern et al. (1997). State-level variables are more likely than individual-level variables to be exogenous to the model. We test the set of identifying instruments to gauge whether they can be validly left out of the maternal health equation and to determine whether they are reasonably strong predictors of the length of maternal leave from work. All models are estimated using several sets of independent variables to see whether the estimates are sensitive to the variables included in the model, some of which may be endogenous.

   We use data from the NMIHS, which includes a national, racially diverse sample of mothers. The McGovern et al. sample is limited to the Twin Cities region of Minnesota, and 91% of the sample respondents...