Objectives To report the incidence of breast abscess in lactating women.
Design Data were combined from two studies (a randomised controlled trial and a survey) to provide a cohort of women for this report.
Setting Women were recruited from two hospitals on one site in Melbourne, Victoria, the Royal Women's Hospital (public) (1999–2001) and Frances Perry House (private) (2000–2001).
Participants A total of 1193 of 1311 (91%) primiparous, English-speaking women from a diverse range of backgrounds, including those receiving public clinic care, private care and birth centre care.
Methods A structured telephone interview was conducted on breastfeeding at six months postpartum.
Main outcome measures Lactational mastitis and breast abscess.
Results Two hundred and seven women experienced mastitis. Five women developed a breast abscess: 0.4% of women who commenced breastfeeding (95% CI 0.14–0.98); 2.9% of women who took antibiotics for mastitis (95% CI 1.0–6.7).
Conclusion Although many authors estimate that 11% of women with mastitis develop a breast abscess, the incidence of lactating breast abscesses in Australia appears to be lower than reported in the past. Our estimate is that 3% of women with mastitis will develop a breast abscess.