In countries like the U.S. and the Netherlands, antidepressants are a commonly prescribed treatment for postpartum depression. But a new study by Princeton University scholars suggests that prescribing rates in some areas of the Netherlands are too high.

This usage is connected to several negative outcomes: mothers are less likely to return to work, they are less likely to live with the father of their child, and they are more likely to birth second child within 30 months following the first. They are also more likely to develop and be treated for other severe psychiatric disorders.

However, selection into antidepressant treatment might be skewing these correlations. For example, one might expect that the most severely ill women would most likely be prescribed antidepressants and would have worse future outcomes. To account for this, the researchers focused their study on women who were more likely to receive antidepressants because they lived in areas with high-prescribing doctors.

They found that postpartum patients on antidepressants were consistently more likely to rely on them up to three years after giving birth, but that there was little effect on other outcomes. They also found that low-income and socially disadvantaged mothers were more likely to live in high-prescribing areas.

The evidence points to an overprescription of antidepressants in certain regions, the researchers report in a working paper published by the National Bureau of Economic Research.

“Treatment with antidepressant drugs has been described as the ‘mainstay’ of treatment for postpartum depression, but most studies have had small or unrepresentative samples,” said co-author Janet M. Currie, the Henry Putnam Professor of Economics and Public Affairs and co-director of Princeton University’s Center for Health and Wellbeing (CHW). “By using a large and representative sample and focusing on a range of outcomes important to women’s well-being, we hope to fill some of the gaps in the past literature.”

To examine the relationship between postpartum antidepressant use and health outcomes, Currie and Esmée Zwiers, a postdoctoral research associate at CHW, used Dutch administrative data of more than 420,000 first-time mothers from 2008 to 2016. They examined both doctors’ tendencies to prescribe antidepressants and several outcomes — including chronic antidepressant use, additional mental illness diagnoses, employment, wages, and the stability of domestic partnerships.

Previous research on postpartum depression suggests the illness can take a significant toll on a mother’s employment, earnings, and lifelong mental health — including an elevated risk of self-harm and thoughts about suicide. This is why many physicians have looked to antidepressants to treat postpartum depression.

To assess the relationship between antidepressant use and future health outcomes, the researchers took advantage of several features of the Dutch health care system. Like the U.S., most antidepressant prescribing in the Netherlands is done by primary care physicians who see patients in their local area. This means that a woman’s residence determines how likely she is to receive antidepressants.

Treatment with antidepressant drugs has been described as the ‘mainstay’ of treatment for postpartum depression, but most studies have had small or unrepresentative samples. ... We hope to fill some of the gaps in the past literature. — Janet Currie

The researchers first focused on how likely doctors in a local area were to prescribe to women aged 46 to 65. They found that the rate that the doctors prescribed to the older women helped predict whether new mothers would receive antidepressants. Women who lived in high-prescribing areas were more likely to receive antidepressants.

With data from Statistics Netherlands, the team then linked predicted postpartum antidepressant use to a variety of measures of the mothers’ life circumstances.

The comparisons suggest that anti-depressant prescribing has little causal impact on most outcomes with one important exception: New mothers prescribed antidepressants were more likely to still be taking the medication three years later.

While the study faced some limitations, the researchers believe their findings suggest that doctors in high-prescribing areas may be overprescribing antidepressants to mothers who receive little benefit from their use. This comes with a cost of long-term dependence on antidepressants.

“In the Netherlands, antidepressants can be prescribed by any general practitioner and are covered by government-mandated health insurance. They are relatively easy to access,” said Zwiers. “Since antidepressants can have harmful side effects like excessive weight gain and elevated blood sugar, it is important that they are only prescribed when they are really needed. Further guidelines surrounding the use of antidepressants as a primary treatment for women experiencing postpartum depression may be needed.”

The working paper “Medication of Postpartum Depression and Maternal Outcomes: Evidence from Geographic Variation in Dutch Prescribing” appeared as a working paper of the National Bureau of Economic Research, a nonprofit research organization.