Mothers who choose to breastfeed their children are around half as likely to develop rheumatoid arthritis compared to women who have never breastfed, researchers said.
The study of more than 7000 women, published in the journal Rheumatology, found that breastfeeding -especially for longer periods - was associated with a lower risk of developing the condition.
Rheumatoid arthritis is a condition that causes pain and swelling in the joints. Sufferers are most likely to be affected in the hands, feet or wrists, but other parts of the body can also be affected.
The condition, which is estimated to affect over 35,000 people in Scotland and occurs more frequently in women than men, can sometimes be very painful, making movement and everyday tasks difficult.
Researchers asked the women, all aged 50 and over and from south China, about their history of breastfeeding and examined them for any signs of the condition.
Around one in 10 were deemed to have rheumatoid arthritis.
Women with arthritis were significantly more likely to be overweight and less likely to have ever breastfed their children, the authors said.
Those who had at least one baby and had breastfed were around half as likely to have rheumatoid arthritis, the researchers said.
They wrote: "We found a dose-response relationship between an increasing duration of breastfeeding and lower risk of rheumatoid arthritis (RA) in this large sample.
"This is the first study to demonstrate a link between breastfeeding and a lower risk of RA in a Chinese population, where breastfeeding is common practice and more prevalent than in many Western populations."