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.

In this study, long-term breast feeding, but not OC use, was associated with a significant reduction in the risk of RA.

A high BMI was associated with a reduced risk of future RA in men, but not in women. Factors related to adipose tissue may contribute to mechanisms that are protective from RA in men.

Lower levels of testosterone were predictive of RF-negative RA, suggesting that hormonal changes precede the onset of RA and affect the disease phenotype.