Contraceptive pill may lower rheumatoid arthritis risk

The Annals of the Rheumatic Diseases has published research which states that taking contraceptive pills for 7 or more years continuously is linked to lower rates of the development of rheumatoid arthritis, with no links of significance found for breast feeding. The disease is up to 3 times more common in women than men, so it is said that reproductive and hormonal factors may explain the difference in gender partly. 

Researchers looked at the possibility of links between the disease development and use of the pill and/or breastfeeding amongst women who had a minimum of one child.  Data was used from the Swedish Epidemiological Investigation of Rheumatoid Arthritis (EIRA), which involved women aged 18 and older living in Sweden between the years of 1996 and 2014.  During this period 5312 women were selected at random from the general populous matched for age as a comparison group, and 2809 women were diagnosed with the disease.

Blood samples were taken from all participants, and the women were quizzed in depth about their medical, reproductive, and contraceptive histories, if they had breastfed, educational attainment, and lifestyles. 4129 women from the comparison group and 2578 women with arthritis were included in the final analysis. 1949 had breastfed, and 884 of these women had rheumatoid arthritis from the comparison group.

Women that used the pill at any time were found to have a lower risk of developing the disease than the others had had never. The risk was 15% lower in current user and 14% lower in former users. Association was significant for those who tested positive for ACPA antibodies compared to those who never used oral contraceptive. 9 out of 10 people of test positive for ACPA antibodies will have rheumatoid arthritis, these antibodies may be an indication of a more serious disease. The average length for using the pill was 7 years. It was found that using the pill for more than 7 years had a 19% lower risk of developing this disease, findings were the same for those who tested both positive and negative for ACPA. It was found that there was a lower risk for women who breastfed, it was not significant after all influential factors were taken into account.

This was an observational study, so no definite conclusions can be made. Researchers were unable to get all the information necessary about the doses or types of pill used by all of the woman as well which adds to this. But researchers note the study was large and included a wide range of potentially influencing factors, which will assist in future studies.