Background As rheumatoid arthritis (RA) occurs more often in women than in men, it has been suggested that reproductive hormones may play an important role in the pathogenesis.

Methods Between 1991 and 1996, 30 447 subjects (18 326 women) were included in a community-based health survey. Information on female hormonal changes and stress-related factors was obtained using a self-administered questionnaire. This population was linked to four different local and national RA registers. The medical records for patients with a diagnosis of RA were subjected to a structured review and all women with incident RA according to the 1987 American College of Rheumatology criteria after inclusion in the health survey were included in a nested case–control study. Matched controls (1:4) were selected from the health survey population.

Results Early age at menopause (≤45 years) was associated with the subsequent development of RA (OR 2.42, 95% CI 1.32 to 4.45). The effect of early menopause remained significant after adjusting for smoking, level of education and length of breastfeeding (OR 1.92, 95% CI 1.02 to 3.64)

Conclusion RA was predicted by an early age at menopause. This implicates an influence of hormonal changes during the fertile period on the development of RA in postmenopausal women.