Childhood exposure to infection may protect women from RA.(Clinical Rounds)

Healthy female babies might not make such healthy adults, at least when it comes to rheumatoid arthritis, according to a group of British researchers.

Exposure to infection in early childhood may help protect women from developing rheumatoid arthritis (RA), reported Dr. C.J. Edwards and colleagues from the University of Southampton and the Southampton General Hospital, United Kingdom.

"It appears that a developing immune system exposed to fewer infectious microorganisms through improved standards of hygiene may be more likely to produce [rheumatoid factor] and perhaps begin the pathological process that leads to [rheumatoid arthritis]," reported Dr. Edwards and colleagues (Ann. Rheum. Dis. 2006;65:401-4).

The researchers' study measured rheumatoid factor levels in 675 men and 668 women aged 61-69 years and investigated the association of rheumatoid factor with markers of exposure to childhood infection.

These markers of exposure included sharing a bedroom during childhood, social class, and birth order.

"Reduced exposure to microorganisms is thought to result from higher social class, fewer siblings, having your own bedroom during childhood, and living in an urban environment," the authors reported.

A positive rheumatoid factor level--defined as 6 IU/ml or higher--was present in 16.6% of the men and 11.8% of the women in the study.