Depressive disorders can develop during or after pregnancy, and studies have shown that they increase risk of maternal suicide and complications such as low birthweight and infant malnutrition. A recent study published in the Lancet Psychiatry identified clinical differences in perinatal depressive symptoms based on symptom type, severity, and timing of onset.
According to the World Health Organization, perinatal depression is defined as the onset of a major depressive episode during pregnancy or the first 12 months postpartum. Although symptoms of depression may differ in type and severity based on the timing of onset, few studies have examined such differences. To address this need, a group of researchers investigated differences by categorizing clinical subtypes of perinatal depression based on type, severity, and timing of onset of symptoms.
The researchers hypothesized that depression experienced during pregnancy would be different in type and severity compared to postpartum depression. To test their hypothesis, they used secondary data previously collected by The Postpartum Depression: Action Towards Causes and Treatment (PACT) Consortium. After screening data from nearly 18,000 unique cases collected at 19 international sites, data from 663 women aged 19-40 collected at seven sites fit the criteria for analysis. Data included onset of depressive symptoms and type and severity of symptoms as measured by the Edinburgh Postnatal Depression Scale (EPDS), which was administered approximately 4.5 months postpartum.
Five subtypes of perinatal depression were identified based on symptom type and severity. Subtypes were further distinguished based on timing of the onset of depressive symptoms. The 10-item EPDS reflected three primary symptom profiles characterized by depressed mood, anxiety, and anhedonia, or inability to experience pleasure from activities previously enjoyed. When severity of symptoms was examined for these three profiles, five subtypes of perinatal depression emerged as follows: severe anxious depression, moderate anxious depression, anxious anhedonia, pure anhedonia, and resolved depression.
Approximately half of the women had either severe or moderate anxious depression, characterized by comorbid symptoms of anxiety that differed in severity. Ninety-eight percent of these women had EPDS scores in the moderate to severe, or very severe range, and the majority endorsed frequent thoughts of self-harm. Nearly a quarter of the sample had either pure anhedonia or anhedonia with symptoms of anxiety (i.e., anxious anhedonia); another quarter had resolved depression that was identified sometime during the prenatal period, but which resolved itself upon EPDS assessment postpartum. The highest proportion of women with EPDS scores in the very severe range belonged to the anxious anhedonia group, and, along with women in the severe anxious depression group, they had the highest scores on the EPDS anxiety subscale.
Onset of symptoms was examined based on each trimester of pregnancy and three postpartum periods (i.e., 0 to <4 weeks, ≥4 to <8 weeks, and ≥8 weeks). In general, women with onset of depressive symptoms in the first trimester had more severe symptoms during the postpartum period as assessed by the EPDS, compared to those who reported onset of symptoms in the second or third trimesters. Depressive symptoms were even more severe for women who reported onset during the postpartum period, especially when onset was reported in the first eight weeks postpartum.
When subtypes were examined in conjunction with timing of onset of symptoms, the researchers found that those with severe anxious depression or moderate anxious depression were more likely to have onset of symptoms in the first trimester or more than 8 weeks postpartum. Women with anxious anhedonia were more likely to have onset of symptoms during the first and second postpartum periods; few of these women experienced onset during pregnancy. In general, those with pure anhedonia did not have onset in the immediate postpartum period, and there was no pattern with regard to the timing of onset for the other prenatal or postpartum periods in this group. Women with depression that was resolved upon EPDS postpartum assessment generally reported onset of depressive symptoms during the third trimester of pregnancy.
While the researchers took a novel approach to identifying clinical subtypes of depression, their study was limited by available data from less than half of the PACT sites, and the results were descriptive in nature only. The EPDS was administered at one point in time, and the pre-pregnancy depression scores of the participants, which could be associated with future scores, were not known. Further, it is possible that other characteristics not studied by the researchers distinguish clinical subtypes. Further validation is required, as the identification of clinical subtypes of perinatal depression suggests that individualized approaches to treatment are needed to address symptom profiles associated with each subtype. These preliminary results suggest that treatment should be tailored based on screening that occurs longitudinally across the course of the perinatal period.
Written By: Suzanne M. Robertson, Ph.D