Exclusive Breastfeeding Duration and Perceptions of Infant Sleep: The Mediating Role of Postpartum Anxiety

(1) Background: Existing literature has identified associations between exclusive breastfeeding, maternal mental health, and infant sleep. This study aims to examine these relationships simultaneously and consider the mediating role of postpartum anxiety. (2) Methods: Participants completed validated measures of postpartum anxiety, infant sleep, and reported exclusive breastfeeding duration. Postpartum mothers with infants between six and twelve months (n = 470) were recruited to a cross-sectional online survey containing a battery of psychological measures. (3) Results: Correlation analyses examined the relationships between the predictor (exclusive breastfeeding duration), outcome (perceptions of infant sleep), and mediator (postpartum anxiety). Exclusive breastfeeding duration was significantly associated with postpartum anxiety (p < 0.05), postpartum anxiety was significantly associated with perceptions of infant sleep (p < 0.001), and exclusive breastfeeding duration was significantly associated with perceptions of infant sleep (p < 0.001). A simple mediation model was conducted, showing a significant total (B = −0.029 (0.010), p < 0.05), direct (B = −0.035 (0.009), p < 0.001), and indirect effect (B = 0.007, SE = 0.003, 95% CI = 0.000 to 0.014) of exclusive breastfeeding duration on perceptions of infant sleep via postpartum anxiety. (4) Conclusions: Associations were identified between exclusive breastfeeding duration, postpartum anxiety, and perceptions of infant sleep. The mediation model suggests postpartum anxiety may be an underlying mechanism which reduces exclusive breastfeeding duration and negatively affects maternal perceptions of infant sleep quality.