Breast feeding for thirteen months or more reduces mother's risk of developing rheumatoid arthritis

Breast feeding for a period of thirteen months or more has been shown to reduce the mother's the risk of developing rheumatoid arthritis (RA), according to new data presented at EULAR 2007, the Annual European Congress of Rheumatology in Barcelona, Spain. In the study, the longer the breast feeding period, the lower the mother's risk of developing RA in later life.

Comparable use of oral contraceptives (OCs) or hormone replacement therapy (HRT) did not show a significant effect on the risk of developing RA.

Lead researcher Dr Mitra Keshavarz, of Malm, Hospital University, Sweden, said of the study, "Whilst other studies suggest that hormonal factors play a part in the development of RA, and we know that pregnancy can result in an improvement in RA symptoms, we wanted to investigate the long term effect of breast-feeding. This study specifically highlights the potential of naturally-induced hormones in protecting individuals from developing RA in the future. Furthermore, it adds to the growing body of evidence in favour of breast feeding and its positive health implications , this time demonstrating its protective benefits for the mother."

The study found that breast feeding for 13 or more months was associated with a reduced risk of developing RA (odds ratio 0.46; confidence interval 95% 0.24-0.91). For women with between 1 and 12 months history of breast feeding, the odds ratio was 0.74, with a 95% confidence interval (0.45-1.20) compared directly to those who had never breast fed.

The data was taken from a community-based health study incorporating information from the Swedish National Hospital Discharge and the National Cause of Death Register between 1991 and 1996, comparing health information from 136 women who later developed RA with that of 544 controls. Information on the use of OCs, HRT and other lifestyle factors was derived from a self-administered questionnaire and analysed by a team from Malm, University Hospital, Sweden.

All females with RA utilised in the case control group of the study were diagnosed according to the 1987 American College of Rheumatology (ACR) criteria for RA. Individuals were matched with four female controls for every case. Controls were identified as those alive and free from diagnosed RA when the index individual was diagnosed with RA.

The median age of the onset of RA in the sample population was 63.3 years, with an average length of 5.5 years between enrolment in the study and onset of RA.