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Aim: Many studies have documented serious effects of postpartum depression. This prospective study sought to determine predictive factors for postpartum depression.
Methods: Pregnant women (n = 239) were enrolled before 24 weeks in their pregnancy. At 6 weeks postpartum, 30 women who had postpartum depression and 30 non-depressed mothers were selected. The Edinburgh Postnatal Depression Scale (EPDS), the Beck Depression Inventory (BDI), the Beck Anxiety Inventory (BAI), the Rosenberg Self-Esteem Scale (RSES) Marital Satisfaction Scale (MSS), and the Childcare Stress Inventory (CSI) were administered to all 60 mothers at 24 weeks pregnancy, 1 week postpartum, and 6 weeks postpartum.
Results: The differences in most of the diverse sociodemographic and obstetric factors assessed were not statistically significant. There were significant differences in MSS scores at 24 weeks pregnancy (P = 0.003), and EPDS (P < 0.001; P = 0.002), BDI (P = 0.001; P = 0.031), and BAI (P < 0.001; P < 0.001) at both 24 weeks pregnant and 1 week postpartum, while there was no significant difference in the RSES scores at 24 weeks pregnant (P = 0.065). A logistic regression analysis was performed on the following factors: ‘depressive symptoms immediately after delivery’ (EPDS and BDI at 1 week postpartum), ‘anxiety’ (BAI prepartum), ‘stress factors from relationships’ (MSS prepartum and CSI at 1 week postpartum) or ‘self-esteem’ (RSES prepartum). When these four factors were added individually to a model of the prepartum depressive symptoms (EPDS and BDI prepartum), no additional effect was found.
Conclusions: The optimum psychological predictor is prepartum depression, and other psychological measures appear to bring no significant additional predictive power.
POSTPARTUM DEPRESSION (PPD) is diagnosed when a mother shows the onset of mood episodes within 4 weeks postpartum.1 Postpartum depression occurs in 10–20% of delivered mothers; childbirth creates a stressful period that may interact with innate vulnerability and environmental factors.2,3 Because of its adverse effects upon the cognitive, social, and emotional development of the child, PPD is considered to be a critical public health problem.
Although many studies have tried to explore the psychosocial predictors of PPD, and have pointed to prepartum depression as a major factor,4 some researchers have focused on sociodemographic factors such as financial/professional difficulties,5 early loss of a parent,6,7 stressful events during pregnancy and delivery,8 and obstetric difficulties.9 Other researchers have emphasized psychological signs such as anxiety,10 marital dissatisfaction,11 self-esteem issues,12 and psychological conditions.13
However, there have been few studies that have controlled for variations in prepartum depressive symptoms which have shown a large effect size (0.49 to 0.51).14 Moreover, most studies have been limited by the use of retrospective methods, small sample sizes, or diagnosis based on self-report scales, making it difficult to comprehend the effects of prepartum conditions and predictive factors.15,16
In this study, statistical differences in sociodemographic and psychological features were explored with the intent of determining whether any other factors besides prepartum depressive symptoms have significant implications on diagnosis. We recruited a large number of pregnant women before their deliveries for prospective observation. After that, we assessed the mothers' sociodemographic and obstetric data during pregnancy, and investigated psychological factors three times between 24 weeks pregnancy to 6 weeks postpartum, because repeated measures would suggest more reliable predictive factors.17 Finally, we administered logistic regression analyses to examine the additional effects of the above factors on the prediction of PPD.
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At the beginning of the present study, 239 pregnant women were enrolled. To detect specific predictive signs or risk factors, sociodemographic data and obstetric information were investigated. In addition, the psychological characteristics were identified prospectively at 24 weeks pregnancy, 1 week postpartum, and 6 weeks postpartum. At 6 weeks postpartum, 30 of the 239 mothers were diagnosed as having postpartum depression based on SCID-I scores. We selected 30 non-depressed mothers of the same subject pool as a comparison group.
The study findings indicate that prepartum depression has good predictive power on postpartum depression. However, there were no additional effects when sociodemographic or obstetric data and other psychological features were considered in the prediction of postpartum depression.
In the study, we failed to find sociodemographic or obstetric predictors that could provide a significant discrimination of the postpartum depression group from the non-depressed group. Although significant differences were found in incomes and nausea (P = 0.006, P < 0.001, respectively), these variances could not be taken as risk factors in that there was no linear feature or distinctive aspect to interpret (Table 1). These results support prior studies that found no relationship between postpartum depression and demographic factors such as age, education, or income.17,29,30
The EPDS, BDI, and BAI scores during pregnancy and immediately after delivery, as well as the MSS during pregnancy and the CSI at 1 week postpartum, showed statistical differences between each other (Table 5). Even though there was no significant difference in the RSES scores between groups, it is not surprising when considering that a previous study suggested that there is no significant relationship between a mother's depression and self-esteem.31 However, the effect of self-esteem on a mother's depression should be examined in further studies, because other researchers have asserted that self-esteem does play a significant role in the onset of clinical depression.32
In the analysis of sensitivity, specificity, and predictive value, the BAI score that was measured at 24 weeks pregnancy had the highest discriminative power (classified 83.7%) among any of the scales, including the BAI at 1 week postpartum (78.0%). Also, the EDPS score at 24 weeks pregnancy accurately classified 79.1% of the depressed mothers, and the EPDS at 1 week postpartum classified 72.5%. The BDI at 24 weeks pregnancy classified 76.7%, and at 1 week postpartum classified 66.7%. The CSI at 1 week postpartum and the RSES at 24 weeks pregnancy classified 72.2% and 72.1% of PPD subjects, respectively. Using the MSS, 75.8% were accurately classified. However, a more important question is which psychological feature, when added to the data on prepartum depressive symptoms, would have a good predictive power for anticipating PPD in a clinical setting. Because depressive symptoms during pregnancy are better correlated to PPD than are any other features, even if another psychological factor had predictive power, we could not consider that factor in isolation to the exclusion of depressive symptoms.
For this reason, logistic regression, a powerful tool for analyzing patient characteristics, was performed to identify the most beneficial variables in predicting postpartum depression. Astonishingly, when ‘depressive symptoms immediately after delivery’ (EPDS and BDI at 1 week postpartum), ‘anxiety’ (BAI prepartum), ‘stress factors from relationships’ (MSS prepartum and CSI 1 week postpartum) or ‘self-esteem’ (RSES prepartum) were added to the prepartum depressive symptoms (EPDS and BDI prepartum), there was no additional effect in the prediction of postpartum depression. These results raise doubts about whether any incidental information besides prepartum depression should be collected and examined to predict postpartum depression, particularly when considering the effort and expense required gathering information from women around the time of childbirth. As shown in Table 5, and in prior studies, the links between depression, anxiety, and other psychological features are prominent, as shown by the increased covariance between variables.33 For these reasons, we would rather focus on prepartum depression, which can be measured by the EPDS and BDI tests, and save resources by not attempting to tap into many factors that have no additional advantage for prediction.
Our findings have clinical implications and consequences about the economical and efficient prediction of postpartum depression as follows. First, it is hard to find any distinctive sociodemographic or obstetric indicators, even considering the mother's anxiety, relationship stress, marital satisfaction, and self-esteem, other than prepartum depression. Therefore, we need to pay close attention to women's depressive symptoms during pregnancy more than to any other factor.34 Second, we used a prospective study, which is the most reliable method to discover the effect of predictive factors on postpartum depression; prior to this study, the prospective method has been poorly applied in Asia, including South Korea. In addition, we selected the groups of women with and without postpartum depression from a large pool in order to minimize the noise in the diagnosis of postpartum depression and make clear the characteristics of both groups. Third, in our prospective study, going one step beyond a simple comparison, logistic regression was applied. This study, which closely examined various factors on PPD to the exclusion of the effect of prepartum depression, could be a great help to determine the most efficient way to predict the disorder.
There are two limitations that should be taken into account in interpreting the findings in this study. First, 60 women comprise the final subjects of this study. Further study will be needed using more subjects and diverse scales in order to assure more robust results. Second, prepartum depression, which was found to be a good predictor, was measured only once, at 24 weeks pregnancy. Future research should also aim to assess various time points during pregnancy in order to find the assessment time frame with the best predictive value for postpartum depression.