HPA axis dysregulation and postpartum depression and anxiety symptoms in breastfeeding vs bottle-feeding parents.

Objective: Hypothalamic-pituitary-adrenal (HPA) axis dysregulation has been implicated in the pathogenesis of perinatal mood disorders. Further, HPA axis response is known to be blunted during breastfeeding. We hypothesized that 1) postpartum depression/anxiety symptoms would be associated with HPA axis dysregulation, indexed by loss of expected adrenocorticotropic hormone (ACTH)-cortisol coupling, and 2) this association would vary by method of infant feeding.

Methods: Participants (N=222) intending to breastfeed were recruited in their 3rd trimester of pregnancy. During a lab visit at 2 months postpartum, depression and anxiety symptoms were assessed (Beck Depression Inventory score ≥14 and/or Speilberger State-Trait Anxiety Inventory score ≥40). Participants then breast or bottle-fed their infants as they would at home. After a 10-minute rest, participants completed the Trier Social Stress Test (TSST), a standardized stressor involving speech and math tasks. Blood ACTH and cortisol were measured 10 minutes after feeding, during each task, and at 10, 20, and 30 minutes of recovery. Multilevel models evaluated whether coupling of ACTH at time j with cortisol at time j+1 differed between those with and without depression/anxiety symptoms, and whether differences varied by feeding method.

Results: Of 205 participants who completed the TSST, 44 had depression/anxiety symptoms at 2-months postpartum. Depression/anxiety symptoms were associated with reduced ACTH-cortisol coupling (adjusted beta: -0.03; p-value: 0.03). Among those who breastfed, those with depression/anxiety showed greater blunting of ACTH-cortisol coupling than those without (adjusted beta: -0.04; p-value: 0.02), while those who bottle-fed had similar coupling patterns regardless of depression/anxiety symptoms (adjusted beta: -0.01; p-value: 0.87).

Conclusion: HPA axis response was blunted in those with postpartum depression/anxiety symptoms, and blunting varied by method of infant feeding. Findings support HPA axis dysregulation in perinatal mood and anxiety disorders. Future research should explore how method of infant feeding influences the relationship between perinatal mood disorders and HPA axis dysregulation. Elucidating the mechanistic pathways underlying perinatal mood disorders can aid in the development of better diagnostic and treatment strategies.