Australian-first study finds pregnancy reduces odds of developing rheumatoid arthritis

Lead author Dr Louise Koller-Smith, who conducted the research at UQ’s Frazer Institute, said it was the first study to investigate the risk profile of rheumatoid arthritis in Australian women.

“We analysed data from more than 40,000 participants involved in the Australian Longitudinal Study on Women’s Health over a 30 year period and assessed those who’d developed rheumatoid arthritis during that time,” Dr Koller-Smith said.

“We found women who’d had fewer children were 29 per cent more likely to develop rheumatoid arthritis, which was exactly the same increased risk as women who smoked,” Dr Koller-Smith said.

“For obesity, the risk increased by 3 per cent for each body mass index (BMI) unit, meaning those with higher BMI were at higher risk.

“Knowing the risks is vital, especially for those who have a direct relative with rheumatoid arthritis and are more susceptible, as this knowledge could help them modify the risks to prevent onset of this disease.”

Rheumatoid arthritis is an autoimmune disease which causes severe joint inflammation and affects 1.1 per cent of the Australian population – more than 70 per cent are women.

Professor Ranjeny Thomas, also from UQ’s Frazer Institute, said the disease has a higher prevalence among women because of hormonal factors and genetics. 

“There’s an increased risk for women with fewer children, as the immune system changes to protect the foetus during pregnancy and making it less likely to attack other areas of the body," Professor Thomas said.

“For some women who already have rheumatoid arthritis, their symptoms disappear during pregnancy – because the disease temporarily turns off.”

Professor Thomas said these findings were important for health professionals to be aware of as Australia's population is ageing, BMI increasing and the fertility rate is falling. 

“We’re at the beginning of uncovering the factors that have the biggest influence on the disease, but we know reducing risk factors through living a healthy and balanced lifestyle can help lower the risk of onset.”

Professor Thomas is recruiting for a clinical trial to improve management of the disease through lifestyle changes in people with recent onset rheumatoid arthritis. 

To register interest, please email fi.thomasresearch@uq.edu.au.

UQ’s Frazer Institute is based at The Translational Research Institute at Woolloongabba.

The research is published in BMC Rheumatology.