Table 2

Reproductive factors and the risk of RA for all cases and by RF status at inclusion: bivariate analysis

Cases n=136Controls n=544All OR (CI)RF-positive OR (CI)RF-negative OR (CI)
Nulliparous30991.001.001.00
Given birth to ≥1 child1064450.75 (0.45–1.24)0.84 (0.44–1.60)0.64 (0.27–1.52)
Normal/late menopause1034441.001.001.00
Early menopause26622.42 (1.32–4.45)1.98 (0.91–4.31)5.00 (1.72–14.51)
Normal/late menarche1254651.001.001.00
Early menarche, <12 years3460.21 (0.06–0.70)0.18 (0.04–0.81)0.28 (0.32–2.52)
No breast-feeding431371.001.001.00
Breast-feeding 1–12 months742970.74 (0.45–1.20)1.07 (0.58–1.95)0.40 (0.16–0.97)
Breast-feeding >13 months191100.46 (0.24–0.91)0.61 (0.28–1.36)0.30 (0.08–1.17)
  • RA, rheumatoid arthritis; RF, rheumatoid factor.