MALMÖ, Sweden—Evidence offers yet another reason for women to breastfeed their babies. Breastfeeding for ≥13 months will halve a woman’s risk of developing rheumatoid arthritis (RA), according to a new study published online in the Annals of Rheumatic Diseases.1 The study also found that taking oral contraceptives or having children (but not breastfeeding) did not offer protection against RA.

"Our data show a decreased risk of RA in postmenopausal women with a history of long-term breastfeeding."—Mitra Pikwer, MD
"Our data show a decreased risk of RA in postmenopausal women with a history of long-term breastfeeding," conclude researchers led by Mitra Pikwer, MD, a rheumatologist at Malmö University Hospital in Sweden. "The effect was dose dependent and remained significant even after adjustment for smoking and level of education."

Dose-dependent protective effect of breastfeeding on RA

The study comprised 136 women with RA with 544 age-matched, RA-free controls. In addition to reduced risk of RA and breastfeeding for >1 year, the researchers found that women who breastfed for 1 to 12 months were also likely to cut their RA risk by 25%.

Exactly how breastfeeding protects against RA is not fully understood, but possible explanations include "long-tern immunomodulation such as the development of progesterone receptors on lymphocytes, dysregulated hypothalmic-pituatary-adrenal-axis, and differences in cortisol concentrations," the study authors suggest. The results show that breastfeeding, not parity, reduces RA risk.

Translating research into practice

"This is just one more study in a growing list of studies that either suggest or show the benefits of breastfeeding to both the mother and the baby," said Donnica Moore, MD, a women’s health expert based in Far Hills, New Jersey. "While I can’t imagine too many women will choose to breastfeed for this reason, women should be told the complete benefits of breastfeeding by their doctors in order to encourage what is best for the mother and the baby."

Reference
1. Pikwer M, Bergström U, Nilsson J-Å, et al. Breast feeding, but not use of oral contraceptives, is associated with a reduced risk of rheumatoid arthritis [published online ahead of print May 13, 2008]. Ann Rheum Dis. 2008; doi:10.11363/ard.2007.084707. http://ard.bmj.com/cgi/content/abstract/ard.2007.084707v2.