Influence of female hormonal factors, in relation to autoantibodies and genetic markers, on the development of rheumatoid arthritis in northern Sweden: a case–control study

Abstract

A longer duration of breastfeeding increased the risk of developing RA, especially among individuals seropositive for ACPA or IgM-RF or carrying the PTPN22 1858T variant. Use of OC for ≥ 7 years was associated with a decreased risk.