Objective: The aim of this study was to identify factors associated with requiring surgical treatment for mastitis or breast abscess in postpartum mothers. Materials and Methods: This was a retrospective cohort study using the Japan Medical Data Center Claims Database. Information on pairs of infants born between April 2012 and December 2016 and their mothers were extracted. Data regarding the baseline characteristics, medical history, medical practice, and prescription drugs of mothers and their infants were collected. Multivariable logistic regression analysis was used to examine factors associated with undergoing surgical treatment. Results: The data of 69,363 eligible mothers were analyzed. The proportion of mothers who were diagnosed with mastitis or breast abscess within 1 year after childbirth was 10.8% (7,516/69,363). There were 114 mothers who underwent surgical treatment within 1 year after childbirth. This was 0.2% of all mothers and 1.5% of those diagnosed with mastitis or breast abscess. Surgical treatment was significantly associated with mothers having their first child (adjusted odds ratio [AOR], 2.58; 95% confidence interval [CI], 1.63-4.07) compared to those with a second or later child; it was also significantly associated with the diagnosis of breast abscess (AOR, 10.38; 95% CI, 5.28-20.40). Conclusions: This was the first report of the prevalence of mastitis or breast abscess and the requirement for surgical treatment among postpartum mothers in Japan. A first diagnosis of breast abscess and having a first child were associated with requiring surgical treatment. Health care professionals providing postpartum care should be aware of these factors.
Keywords: breast abscess; breastfeeding; lactation; mastitis.