After item reduction, the Modified Kendler Social Support Interview (MKSSI) was internally consistent and demonstrated construct and external validity in a large cohort of pregnant women. Additionally, a high MKSSI score was significantly correlated to decreased odds of depression in the first trimester of pregnancy, providing excellent external validation of this interview.
While the relationship between social support and depression was significant in both the Kendler (Kendler et al., 2005
) and our study, the results of our principal components analysis and hence items retained for our social support score were different. In Kendler et al. (2005)
, all frequency questions and social integration were deemed relevant to the “global social support” principal component, whereas our data showed that frequency of contact items for mother and father only were related to global social support. We can infer that for our subjects, frequency of contact from only their mother or father was important to overall social support. Additionally, frequency of contact with clubs/church was not significant to overall support. This information would be helpful in the creation of social support interventions for pregnant women, where we may hypothesize that perception of social support from parents would need to address contact with the subject, while interventions with other social relationships would not need to focus on that aspect of support.
The variation in items we retained in our study versus the Kendler study (Kendler et al., 2005
) can be a result of either or both different analytic techniques or group differences. As the actual factor loadings are not presented in the Kendler study, perhaps different levels of significance were used for item loadings. Additionally, we included subjects missing certain categories of relationships, such as those having a deceased father, instead of excluding them from the analysis as in the Kendler study. Therefore, subjects missing certain categories of relationships still received a score on the interview in that category. Finally, perhaps the items that did not load are less relevant to our cohort, as our cohort varied dramatically in age and gender from the initial study. As a result of this difference, we would suggest eliminating these items from the MKSSI for future analysis of social support in pregnant women.
Social support has been theorized to consist of several different measurable domains from both sociological and psychological perspectives (House, 2002
, Schwarzer and Leppin, 1992
). While different hypothesized types of social support, in addition to sources of support, were measured in our analysis, our subjects perceived the construct of support according to source of support as compared to the various qualities of emotional support or frequency of support. This is frequently seen in social support literature (Turner, 1992
) and consistent with the Kendler study (Kendler et al., 2005
). We can elaborate that this is a good measure of general perceived social support from particular sources of support, such as mother or father, and that each relationship has a different strength and nature of support to our pregnant subjects. Therefore, it is important to evaluate and score each of these categories separately in the overall construction of the summed scale, rather than use a broad evaluation of relationships such as Family. The significance of each source of support was further illuminated by logistic regression. All individual sources of support except siblings showed a statistically significant relationship to depression. However, it remains that the combination of these scores provides the strongest association with depression. That these results were similar to the original Kendler factor structure of subscales and their relationship to depression reinforces the validity of the scale modification.
This was the first study of social support and depression in pregnancy to utilize a diagnostic interview for depression using current DSM IV diagnostic criteria. Other studies have used either depression symptom severity measures (Cutrona, 1984
) or screening questionnaires that are not able to diagnose depression specifically but can be elevated by general emotional distress, concurrent psychiatric illness or general medical conditions (Fechner-Bates et al., 1994
; Yonkers and Sampson, 2000
). They are highly subjective and can be biased by a few symptoms that may be far more severe than others.
The health risks of depression in pregnant women may be uniquely harmful. Depression in pregnancy has been implicated as a risk factor for many problems such as poor weight gain, late or delayed prenatal care, self-neglect (c.f. Stewart et al., 2006
for review (Stewart et al., 2006
; Zuckerman et al., 1989
)), poor birth outcomes (Hedegaard et al., 1993
; Misra et al., 2001
; Orr et al., 2002
; Paarlberg et al., 1999
; Reeb et al., 1987
; Steer and Scholl, 1992
; Zimmer-Gembeck and Helfand, 1996
), and postpartum depression (Dietz et al., 2007
). Women who are depressed have a higher prevalence of comorbid poor health habits such as cigarette smoking, drug and alcohol use (Dietz et al., 2007
; Zuckerman et al., 1989
). In 2000-2002, the British Confidential Enquiry into Maternal Deaths described psychiatric illness as the leading cause of maternal deaths overall (RCOG, 2004
). In their extensive review, Fields et al. detail the constellation of negative behavioral, physiological, and biochemical effects that depression during pregnancy has on the developing child (Fields et al., 2006
). It is clear that the need for instruments to anticipate depression in pregnancy is great.
We have focused on the need to predict depression because social support interventions have been evaluated with little success in preventing poor birth outcomes (Hodnett and Fredericks, 2003
). Perhaps depression is a mediator/moderator of the relationship between low social support and poor birth outcomes and by screening for low social support and then managing depression that we may address this association.
There are several limitations to this study. Feasibility dictated that only perceived social support can be evaluated by the MKSSI. Self-report measures are difficult to verify and may be more influenced by personality, mood, or anxiety disorders than actual social support received. Additionally, although external validity of the MKSSI has been established using the CIDI, convergent validity cannot be established with another social support instrument, as there is no gold standard social support scale.
Because this is a cross-sectional study, we cannot claim that low social support precedes depression. In order to determine if high social support protects a subject from depression onset, this study must be longitudinal and beginning with a group of subjects who have no current symptoms of depression.
Furthermore, in our model we did not control for prior history of depression. It would be important to see how a prior history of depression would influence the relationship between depression and social support, especially in a longitudinal analysis. In the Kendler study (Kendler et al., 2005
), it did not affect the magnitude of the relationship; it increased the baseline risk of depression in the subjects.