Post-breastfeeding stress response and breastfeeding self-efficacy as modifiable predictors of exclusive breastfeeding at 3 months postpartum: a prospective cohort study

The rate of exclusive breastfeeding at 3 months postpartum is only 50% in Japan. In order to increase this rate, we aimed to examine modifiable factors related to exclusive breastfeeding at 3 months postpartum by focusing on breastfeeding-related and psychosocial variables at 1 month postpartum. This prospective cohort study was conducted at a secondary medical care center in Osaka, Japan from February 2017 to October 2018. Demographic variables, infant feeding modality, breastfeeding-related variables, and psychosocial variables were obtained using questionnaires at 1 month postpartum. Daytime salivary cortisol levels before and after breastfeeding at 1 month postpartum were measured as a biological marker for stress responses associated with breastfeeding. Each infant's feeding modality was re-assessed at 3 months postpartum. Multiple logistic regression analyses were performed to examine factors affecting exclusive breastfeeding at 3 months postpartum. Of the 104 participants, 61 reported exclusive breastfeeding at 3 months postpartum. The following factors were significantly associated with exclusive breastfeeding at 3 months postpartum: multiparity (adjusted odds ratio, 95% confidence interval: 11.13, 2.08-59.59), having a university degree (5.25, 1.04-26.53), no plan to return to work by 6 months postpartum (0.02, 0.00-0.46), and exclusive breastfeeding (42.84, 6.05-303.52), lower cortisol level after breastfeeding (0.00, 0.00-0.02), and higher breastfeeding self-efficacy scale score (1.07, 1.00-1.14) at 1 month postpartum. In parity-specific analyses, exclusive breastfeeding (25.33, 4.75-134.98) and lower cortisol level after breastfeeding (0.00, 0.00-0.21) at 1 month postpartum in primiparous women, and lower cortisol level after breastfeeding (0.00, 0.00-0.94), higher breastfeeding self-efficacy score (1.18, 1.05-1.32), and absence of breast complications (0.09, 0.01-0.82) at 1 month postpartum in multiparous women were associated with exclusive breastfeeding at 3 months postpartum. Stress levels after breastfeeding, breastfeeding self-efficacy, and the presence of breast complications could be modifiable factors associated with subsequent exclusive breastfeeding. Further research is needed to examine whether approaches to reducing breastfeeding-related stress, improving breastfeeding self-efficacy, and preventing breast complications during lactation are effective to increase exclusive breastfeeding practices.