Objective: To investigate whether there are underlying factors, other than breastfeeding behaviours, which may contribute to the development of breast abscess during the year following delivery.
Design: A population-based study.
Setting: In Sweden.
Population: The 1,454,068 singleton deliveries during 1987-2000. Methods Data retrieval from two national patient registers: the Medical Birth Registry and the National Discharge Register. Stratified Mantel-Haenszel analysis.
Main outcome measures: Odds ratios with 95% confidence intervals for possible risk factors for breast abscess in the year following delivery.
Results: During the year following delivery 1401 women had surgery because of a breast abscess. This gives a rate of 0.1%. Sixty-five percent of cases occurred between three and eight weeks postpartum. An annual increase in the odds ratio (OR) was found between 1993 and 1999. Lowest risk was found among mothers who were < or =24 years and a significantly increased risk among mothers > or =30 years. There was a 3.6-fold increased risk for breast abscess associated with primiparity and OR for post-maturity (>41 weeks) was 5.
Conclusion: Primiparous women appear to be at a greater risk for the development of breast abscess during lactation than multiparous women. Mothers over the age of 30 years and those who give birth post-maturely are also at a significantly increased risk. Primiparous women and women over 30 years could be targeted for extra information in preparation for parenthood classes about how to avoid over distension of the breasts during breastfeeding. Further research is needed to understand the role of post-maturity and to investigate why some women recover spontaneously from inflammatory processes of the breast.