Comorbidities may play a large role in driving poor pregnancy outcomes in pregnant people with certain immune-mediated inflammatory diseases (IMIDs).
In a new study of 12 individual IMIDs, people with rheumatoid arthritis (RA) or inflammatory bowel disease (IBD) did not have signficantly increased risk for preterm birth (PTB) or low birth weight (LBW), compared with people who did not have an IMID, after adjusting for additional chronic conditions and other confounding factors.
Dr. Jennifer Hadlock
The study was published online on February 1 in eClinicalMedicine.
While many studies have explored the relationships between pregnancy outcomes and IMIDs, “the impact of comorbidities on the relation between IMIDs and pregnancy course is insufficiently examined,” the authors wrote. These previous studies also tended to have a small sample size.
Pregnancy Outcome Risks Varied Between IMIDs
To remedy this, researchers used electronic health record data from Providence St Joseph Health — a multistate integrated healthcare system — to identify more than 365,000 pregnant people with live births between January 1, 2013, and December 31, 2022. The cohort included more than 5700 people with at least one of 12 IMIDs: Psoriasis, IBD, RA, spondyloarthritis (SpA), multiple sclerosis, systemic lupus erythematosus (SLE), psoriatic arthritis (PsA), antiphospholipid syndrome (APS), Sjögren syndrome (SjS), vasculitis, sarcoidosis, and systemic sclerosis. The study included only live births with a gestational age of 20 weeks or greater.
Researchers compared maternal-fetal health outcomes between the two groups, controlling for comorbidities including diabetes, cardiovascular disease, chronic kidney disease, obesity, and depression. They also accounted for confounding variables including race, age, smoking status, and socioeconomic status.
In total, 83% of people in the IMID group had no immunomodulatory medication prescriptions during their pregnancy. Of the 17% taking medication, 48%-70% continued taking their medication until delivery. Most patients were White, comprising 62.9% of the non-IMID group and 73.1% of the IMID group.
After adjusting for comorbidities, patients with any of the 12 IMIDs had a 10%-20% higher risk for PTB, LBW, small for gestation age (SGA), and cesarean section than did comparators.
But these risks varied between IMIDs. Patients with RA and IBD did not have an increased risk for PTB or LBW. However, when researchers did not control for comorbidities, pregnancy risks were higher and showed statistical significance in these two groups.
“This suggests that for RA and IBD, comorbidities may be a more important factor for adverse outcomes than the underlying autoimmune disease,” senior author Jennifer Hadlock, MD, an associate professor and director of medical data science at the Institute for Systems Biology in Seattle, Washington, said in a video accompanying a press release.
Overall, the analysis found that women with IMIDs were approximately two to three times more likely to have chronic comorbidities than the control group.
Like previous studies, there was a strong association between SLE and APS and poor pregnancy outcomes, even after controlling for confounding factors. Patients with SpA had a 50% increased risk for PTB, while those with SLE and APS had more than a twofold higher risk. Patients with SLE were 90% more likely than comparators to deliver babies with an SGA condition, while RA patients had a 30% higher risk. SLE was the only condition with an increased risk for LBW (relative risk, 3.5). IBD, RA, PsA, SpA, SLE, APS, and SjS were all associated with a higher likelihood of delivery via cesarean section.
“The findings of this study reveal that the associations between IMIDs and adverse pregnancy outcomes are influenced by the specific type of IMIDs and the presence of comorbidities,” the authors wrote.