Rheumatic diseases of joints, muscles or connecting tissues can lead to reproductive problems like childlessness, preterm birth and birthing children of low weight, new research has found.

Published in the journal Rheumatology, the study examined the impact of autoimmune diseases on reproductive health using data from Finnish nationwide registers.

For a person suffering from an autoimmune disease, the body’s immune system mistakenly attacks healthy tissues and organs.

Authors of the study measured reproductive health in terms of number of children and adverse maternal and pregnancy-related outcomes for such patients.

The researchers found that among those born in Finland between 1964 and 1984, roughly 8 per cent of women and the same percentage of men had an autoimmune disease diagnosed before or during reproductive years.

While many of these autoimmune diseases had little impact on the number of children, women having selected conditions were found to experience a higher prevalence of childlessness.

The team found that the top three diseases having the maximum impact were Addison’s disease (23.9 per cent more childlessness), juvenile idiopathic arthritis (9.3 per cent), and vitamin B12 deficiency anaemia (8.6 per cent).

Addison’s disease is a disorder in which the adrenal glands do not produce enough hormones, while juvenile idiopathic arthritis is an arthritic condition affecting children or juveniles.

“Despite seeing an elevated risk for diverse childbearing problems in rheumatic and other immune-mediated diseases, many of the complications are still fairly rare,” said the study’s lead author Anne Kerola from University of Helsinki in Finland.

Several rheumatic diseases lead to higher rates of childlessness and fewer children, and on average, people with such diseases tend to have preterm deliveries, the researchers found in their case-control study.

The study also found that men with rheumatic conditions experienced more childlessness than controls, with most diseases showing no difference but some diseases resulting in much higher prevalence of childlessness.

The team said the top three such diseases were myasthenia gravis (20.1 per cent more childlessness), Addison’s disease (16.4 per cent), and vitamin B12 deficiency anaemia (13.7 per cent).

Myasthenia gravis is a condition in which antibodies prevent nerves and muscles from communicating with each other, thereby weakening the skeletal muscles.

“Family planning should actively be discussed between patients, both men and women, with rheumatic diseases and their healthcare providers. Pregnancies in women with rheumatic diseases are carefully followed up to tailor medications appropriately, which helps reduce risks,” said Kerola.