The association between breastfeeding, the stress response, inflammation, and postpartum depression during the postpartum period: Prospective cohort study

Background: Research suggests that exclusive breastfeeding may have a stress-protective role in postpartum depression; however, less is known about the underlying mechanisms by which this protection may occur or whether the protective relationship holds for women who mix breast and bottle feeding. Objectives: To examine patterns of the stress response, inflammation, and depressive symptoms among women predominantly breastfeeding or bottle feeding their infants at 6 months postpartum. Design: A part of a larger longitudinal study across 6 months postpartum investigating the psychoneuroimmunology (PNI) of postpartum depression. Setting: Prenatal clinics and community. Participants: One hundred nineteen postpartum women who met inclusion/exclusion criteria and followed up from the prenatal period to postpartum 6 months. Methods: Data were collected during seven home visits occurring during the 3rd trimester (weeks 32-36) and on postpartum days 7 and 14, months I, 2, 3, and 6. Women completed stress and depression surveys and provided blood for pro- (IL-1 beta, IL-6, IL-8, TNF-alpha, IFN-gamma) and anti-inflammatory (IL-10) cytokines, and collected saliva for diurnal cortisol. Results: Self-report of predominant breastfeeding during 6 months postpartum ranged from 91.9% at day 7 to 70.6% at month 6 postpartum. There were no associations between the pattern of feeding and depressive symptoms. Biological differences, however, existed between the groups, with levels of salivary cortisol at 8 AM and 8:30 AM at month 6 higher and levels of IL-6 at month 6 lower in women who primarily breastfed compared to those who primarily bottle fed their infants after controlling for confounding variables. Conclusions: Breastfeeding was not related to postpartum depression however differences in stress and inflammatory markers are apparent at month 6 postpartum. (C) 2015 Elsevier Ltd. All rights reserved.