Rheumatoid Arthritis (RA) is an auto-inflammatory disease that particularly involves chronic inflammation of the joints.The disease is in essence a systemically active one that can affect almost any organ. Pregnancy can spontaneously reduce the activity of RA. This phenomenon has been investigated in the PARA-study (Pregnancy-induced Amelioration of Rheumatoid Arthritis study), a nationwide prospective cohort study initiated and coordinated by the department of Rheumatology, Erasmus University Medical Center, Rotterdam the Netherlands.