Does Birth Control or Breastfeeding Reduce RA Risk? Save

 Researchers have reported their case-control study using the Swedish Epidemiological Investigation of RA study (2641 cases/4251 controls) to examine  the influence of oral contraceptive (OC) use or breastfeeding on the risk of rheumatoid arthritis (RA). 

After controlling for ACPA positivity, that found that ever and past OC users had a decreased risk of ACPA-positive RA (OR=0.84 (95% CI 0.74 to 0.96) compared with never users. No significant associations were found for ACPA-negative RA.

Long duration of OC use (>7 years vs never use) decreased the risk of both ACPA-positive (p=0.0037) and ACPA-negative RA (p=0.0356).

Breastfeeding history decreased the risk only of ACPA-positive RA in a dose-dependent manner (p=0.0086), but this trend did not remain after adjustments.

A significant interaction was observed between the lack of OC use and smoking (AP=0.28 (95% CI 0.14-0.42)) on the risk of ACPA-positive RA. No interactions were found for breastfeeding.

OC decreased the risk of RA, especially ACPA-positive RA, and longer OC use.  They could not confirm an association between breastfeediung and a decreased risk of either ACPA-positive or ACPA-negative RA.