Perinatal depression is a common but serious mood disorder. The DSM-5, which is the classification system used to diagnose mental disorders, defines perinatal depression as a depressive episode with onset during pregnancy or in the first 4 weeks after pregnancy (postpartum). However, pregnancy and the postpartum period are associated with several hormonal, behavioral, and emotional changes. Combining them into a single disorder can make studying and treating depression more difficult. Also, limiting the postpartum period to the first month after delivery can miss out on many women who continue to experience depressive symptoms beyond this time.
New research funded by the National Institute of Mental Health examined the current classification of perinatal depression by looking at population-level depression rates over an extended period. The study, led by Veerle Bergink, MD, Ph.D., at the Icahn School of Medicine at Mount Sinai and Erasmus Medical Center, compared depressive episodes among new mothers before, during, and after pregnancy.
The researchers used data from population registries in Denmark to identify 392,287 women who had given birth for the first time between 1999 and 2015. Only births of the first child were included to avoid counting the same woman more than once. . Then, the researchers calculated the number of first-time and repeat depressive episodes the women experienced during each of the following months, reflecting three separate periods:
- 12 months before pregnancy (preconception)
- 9 months before birth (pregnancy)
- 12 months after birth (postpartum)
Initial and repeat depressive episodes were classified according to the number of times women sought psychiatric care for a new depressive episode or after receiving previous treatment for depression. The researchers calculated these rates separately for treatment at outpatient and inpatient psychiatric facilities. In this study, the majority of treatment took place in outpatient settings, reflecting care for moderate to severe depression, with only the most severe episodes treated in inpatient settings.
Overall, treatment rates for first depressive episodes exceeded rates for recurrent depressive episodes, regardless of period (preconception, pregnancy, or postpartum). This was especially true during the postpartum period. Depressive episodes first treated in outpatient and inpatient settings increased markedly after delivery and peaked at 2 months postpartum. The number of office visits for first depression was also higher during pregnancy (especially in the second trimester) than before pregnancy.
Outpatient and inpatient visits for repeated depression were relatively consistent from month to month in both the preconceptional and postpartum periods. However, women who had previously received treatment for depression sought more outpatient care for depression during pregnancy than before pregnancy. In contrast to initial depressive episodes, for which treatment rates were highest in the postpartum period, for recurrent depressive episodes, the majority of outpatient visits were received during the second trimester of pregnancy.
The results of this study support the idea that pregnancy and postpartum are risky periods for maternal mental health. The results also indicate a change in depressive episodes from pregnancy to after birth, specifically, a high occurrence of new depressive episodes in the second trimester of pregnancy and in the first 5 months after delivery. This finding may have important implications for clinical care. A high rate of depressive episodes during pregnancy and postpartum underscores the vulnerability of both periods for new mothers and the need for access to readily available and comprehensive mental health care.
Additionally, the data showed a significant increase in depression treatment in the postpartum period as well with rates higher than those during pregnancy or before conception for several months after delivery. Because this is outside the clinical window in which perinatal depression can be officially diagnosed, the authors suggest extending evaluation of depression beyond 4 weeks postpartum, which could identify many more women who could benefit from treatment. Distinguishing between pregnancy-onset depression and postpartum-onset depression could also refine the diagnoses to better capture the differences in their rates and presentation.
While the findings add to our knowledge of depression occurring before, during, and after pregnancy, the study has some limitations. For example, the researchers analyzed population data from Denmark, a country with specific perceptions and systems of mental health care, and the results may not be generalizable to other countries. Additionally, the sample was limited to women who had given birth for the first time and were experiencing depressive episodes at the more severe end of the spectrum (those treated in psychiatric facilities). The incidence and recurrence of depression may differ for women who have already given birth or with milder forms of depression.
More research is needed to understand how rates of depression vary in different places and for different groups. Population-level studies that systematically explore depression and other mental health disorders can provide insights that lead to better diagnosis and treatment.
Molenaar, NM, Maegbaek, ML, Rommel, A.-S., Ibroci, E., Liu, X., Munk-Olsen, T., & Bergink, V. (2023). The incidence of depressive episodes differs before, during, and after pregnancy: a population-based study. Journal of Affective Disorders, 322273276. https://doi.org/10.1016/j.jad.2022.11.031
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