Women who experience infertility without undergoing fertility treatments may be at a higher risk of developing systemic autoimmune rheumatic diseases (SARD) in the years following childbirth, a new study has revealed.
Published today in Human Reproduction, one of the leading journals in reproductive medicine, the study found that this increased risk persists even when factors like pre-eclampsia, preterm birth, and stillbirth—conditions that are often associated with infertility—are taken into account.
Conducted by researchers at the University of Toronto Scarborough, the study suggests that doctors should be aware that women with infertility may be at risk for undiagnosed or untreated SARD. These diseases occur when the immune system attacks the body’s own tissues, causing conditions such as systemic lupus erythematosus, Sjögren’s syndrome, and inflammatory myopathy. SARD primarily affects women, particularly during their reproductive years.
The research, led by Dr. Natalie V. Scime, analyzed data from 568,053 singleton births between 2012 and 2021. The study included 465,078 women aged 18 to 50 with no prior history of SARD. Researchers used health data from Ontario’s publicly funded insurance system, which tracks nearly all female residents in the province, ensuring that the findings are representative of the population.
The study divided women into four groups: those who conceived naturally without infertility (88% of the group), those who experienced infertility but did not use fertility treatments (9.2%), those who had non-invasive fertility treatments like ovulation induction (1.4%), and those who had invasive procedures like in vitro fertilization (IVF) (1.4%). The researchers tracked the women’s health for an average of 6.5 years, adjusting for factors such as age, pre-existing conditions, and reproductive history.
The findings were striking. Women who experienced infertility without fertility treatments were 25% more likely to develop SARD up to nine years after childbirth. This was in comparison to women without infertility, even after accounting for complications like pre-eclampsia or stillbirth. For every 10,000 women followed for a year, nine new cases of SARD were reported in women without infertility, while 13 new cases were seen in women with infertility who did not use fertility treatments. In contrast, women who used fertility treatments had similar rates of autoimmune diseases as those without infertility, with 11 new cases per 10,000 women.
Dr. Scime speculated that women who used fertility treatments might be healthier overall, which could explain why they did not show an increased risk of SARD. These women may also have better access to healthcare, reducing their overall risk.
The researchers emphasize that while the study found a link between infertility and SARD, it does not suggest that infertility directly causes these autoimmune diseases. Infertility can arise from various factors, including conditions like endometriosis, anatomical abnormalities, or advanced maternal age. The researchers also noted that their study lacked detailed information on the specific causes of infertility, which could have provided more insight into the findings.
In addition, the study had limitations, such as a lack of data on social and lifestyle factors that could influence health outcomes. However, the large sample size of the study is a significant strength.
Dr. Hilary Brown, Associate Professor at the University of Toronto and supervisor of the research, highlighted the importance of the findings for future studies. She suggested exploring whether certain causes of infertility are more strongly linked to SARD risk and investigating the biological pathways that might explain how SARD could affect female fertility.
This research underscores the importance of early detection and diagnosis of SARD, particularly in women with a history of infertility, as early treatment can prevent organ damage and improve long-term health outcomes.
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