A new study has suggested that women who breastfeed may reduce their risk of developing rheumatoid arthritis by half.

Sweden's Malmo University Hospital compared 136 women with the condition with 544 who did not have it. Women who had breastfed for 13 months or longer were half as likely to develop rheumatoid arthritis as those who had never breastfed. Those who breastfed for between one and 12 months had a 25 per cent decreased risk.

No protective effect was noted from simply having children and not breastfeeding, or from taking oral contraceptives.