Mastitis among lactating women: occurrence and risk factors.

Puerperal mastitis is a potentially serious illness among lactating women which traditionally has been thought to be associated with primiparity, stress, improper nursing technique, and incomplete emptying of the breast. However, none of these putative associations has been examined analytically in recent years. Further, the incidence of mastitis in the United States has not been estimated since 1975, although the prevalence of breastfeeding has increased dramatically since then. In this retrospective cohort study of 966 lactating women, the cumulative incidence of mastitis in the first seven weeks postpartum was 2.9%. This incidence was associated with professional, technical, or managerial occupation in both parents (rate ratio = 12.29; 95% CI: 1.62, 93.43) and with giving birth in the hospital delivery room, rather than the labor room (rate ratio = 4.05; 95% CI: 0.92, 17.83). Parity was not associated with risk of mastitis in this sample.