- Women with rheumatoid arthritis negative for anti-cyclic citrullinated peptide and rheumatoid factor are more likely to improve during pregnancy, whereas in autoantibody-positive women autoantibody levels are not influenced by pregnancy. de Man, Y.A., Bakker-Jonges, L.E., Goorbergh, C.M., Tillemans, S.P., Hooijkaas, H., Hazes, J.M., Dolhain, R.J. Ann. Rheum. Dis. (2010)