Date

June 2013

Document Type

Thesis

Degree Name

M.P.H.

Department

Dept. of Public Health and Preventive Medicine

Institution

Oregon Health & Science University

Abstract

Background: Breastfeeding has been associated with numerous health benefits for both mother and infant. For mothers, associated benefits include decreased risk of diabetes, arthritis, and breast cancer. For infants, breastfeeding has been associated with reduction in the risk of otitis media, respiratory tract infections, gastrointestinal infections and obesity. Postpartum depression has been associated with poor mood, lack of energy and recurrent depression among mothers. For infants, postpartum depression has been associated with inhibited language development and behavioral problems. Several studies have found an association between postpartum depression and breastfeeding. Perinatal depression and postpartum depression have been found to be associated with decreased breastfeeding initiation and duration. This association has not been studied among Oregon mothers. The first aim of this thesis is to identify the prevalence of any breastfeeding for at least eight weeks and the prevalence of self-reported postpartum depressive symptoms (SRPPDS) in Oregon mothers. Additionally, we aim to identify whether breastfeeding for at least eight weeks is associated with decreased risk of postpartum depressive symptoms among Oregon mothers. Finally, this thesis explores the question of a causal association between breastfeeding and self-reported postpartum depressive symptoms. Methods: Responses from the 2007 Oregon Pregnancy Risk Assessment Monitoring System (PRAMS) were used to evaluate the association between breastfeeding for at least eight weeks and self-reported postpartum depressive symptoms. In 2007, 1894 mothers completed surveys out of the total of 3067 mothers sampled for PRAMS wielding a weighted response rate of 67%. Logistic regression with forward stepwise variable selection method was used to identify potential independent predictors of postpartum depressive symptoms. Women were excluded if information was missing regarding depressive symptoms or breastfeeding initiation and continuation. A total of 1759 mothers responded to all questions regarding breastfeeding and depressive symptoms and were included in analysis. All data analysis was conducted with sampling weights to account for sampling methods, non-response, and sampling bias. Model building and diagnostics were performed according to the methods of Hosmer & Lemeshow. @Results: @Among respondents in this analysis, 13.5% reported postpartum depressive symptoms and 72.2% reported breastfeeding for at least eight weeks. The prevalence of depression among mothers who breastfed for at least eight weeks was 7.9% compared with a prevalence of 16.2% among mothers who breastfed less than eight weeks. Breastfeeding for at least eight weeks was reported by 77.2% of Oregon mothers. Oregon mothers who breastfed less than eight weeks were 1.6 times more likely to have self-reported postpartum depressive symptoms than mothers who breastfed at least eight weeks (95% CI: 1.004-2.57) adjusting for maternal age, family income, current smoking status, and body mass index. Stressful life events were found to be an effect modifier of this association. Among women who reported no stressful life events, mothers who breastfed less than eight weeks were 4.81 times more likely to report postpartum depressive symptoms than mothers who breastfed at least eight weeks (95%: 2.28-10.17). Among mothers who reported at least one financial stressful life event, the odds of self-reported postpartum depressive symptoms in mothers who breastfed less than eight weeks were 1.18 times the odds of self-reported postpartum depressive symptoms in mothers who breastfed at least eight weeks (95%: 1.02-1.37). Discussion: In Oregon mothers, postpartum depressive symptoms were 60% more likely among those who breastfed for less than eight weeks compared with those who breastfed for at least eight weeks. When mothers report any financial stressful life events the odds of postpartum depressive symptoms is 18% higher in mothers who breastfed for less than eight weeks compared with mothers who breastfed for at least eight weeks. Stressful life events were a significant effect modifier of the association between breastfeeding at least eight week and postpartum depressive symptoms. In the absence of stressful life events the odds of depressive symptoms increases significantly in mothers who breastfeed for less than eight weeks compared with mothers who breastfed for at least eight weeks. An evaluation of the literature suggests multiple potential causal associations. There is some evidence that breastfeeding causes a decrease in risk of postpartum depressive symptoms and there is evidence that postpartum depressive symptoms cause a decrease in breastfeeding practices. It is most likely that causality is working in both directions. Conclusion: Oregon mothers who breastfed for less than eight weeks were more likely to report postpartum depressive symptoms. This relationship remained significant after adjusting for demographic and behavioral characteristics family income, body mass index, current smoking status, and maternal age. These findings are consistent with other studies. Evaluation of these studies supports the possibility of a bidirectional causal relationship between breastfeeding and postpartum depressive symptoms.

Identifier

doi:10.6083/M4CJ8BHN

School

School of Medicine

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