Postnatal Depression and Oxytocin: Naturalistic and Experimental Studies

Postnatal depression (PND) is of public health importance due to its prevalence and mental health challenges. Chapter 1 reviews its diagnosis, risk factors, treatment options and impact on the mother and child. Chapter 2 extends this through a study investigating the role of shame in PND (Study 1), as a psychological factor. This comprised a survey related to PND, shame, and mother-infant bonding. N = 340 new mothers took part. We demonstrated shame mediates the impact of PND on mother-infant bonding difficulties. Chapter 3 then shifts to review a biological factor in PND: the hormone oxytocin (OT). OT is a promising candidate mechanism for understanding why some women develop PND and how it affects the mother and infant. Through a psychobiological framework, Chapters 4-7 then report a series of empirical investigations of OT in maternal mood, mindmindedness, infant development and breast milk in PND. To introduce these, Chapter 4 explores the ethical aspects of the study designs. Chapter 5 tests maternal mindmindedness and demonstrates this is disrupted by maternal low mood (Study 2a), is associated with infant OT (Study 2b), and predicts infant OT but does not mediate an effect of maternal mood on infant OT (Study 2c). We also demonstrate OT inhalation does not impact mindmindedness (Study 3). In Chapter 6, we test maternal breast milk OT and find this is not associated with maternal low mood (Study 4a), is associated with infant OT (Study 4b), and does not mediate an effect of maternal mood on infant OT (Study 4c). We also demonstrate OT inhalation impacts breast milk OT in controls but not in women with PND (Study 5). In Chapter 7 we demonstrate OT inhalation impacts maternal negative mood in controls but not in women with PND (Study 6). The final chapter discusses these findings and their implications