Pregnant women with rheumatoid arthritis (RA) are more likely to have poorer maternal and neonatal outcomes than women with spondyloarthritis (SpA) or no inflammatory arthritis, according to research published in the Journal of Rheumatology.

Researchers examined data collected from the Alberta Pregnancy-Birth Cohort to assess maternal and neonatal outcomes in women with and without inflammatory arthritis. The cohort included 312,081 women and corresponding birth events. Participants were assigned to 1 of 3 groups: no inflammatory arthritis (n=308,989), RA (n=631), and SpA (n=2461). The data set included all live, singleton births between 2005 and 2014; among women with multiple birth events, 1 birth was randomly selected. The primary study outcomes were rates of infants born small for gestational age (under the 10th percentile birth weight) and hypertensive disorders in pregnancy, including preexisting hypertension, pre-eclampsia, eclampsia, and gestational hypertension.

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The investigators found that pregnant women with RA experienced worse neonatal and maternal outcomes compared with those who had SpA and those without inflammatory arthritis. In particular, women in the RA group were significantly more likely to experience a pre-term delivery or an elective or emergent cesarean section (13.5% and 33.9%, respectively), while women with SpA had the highest rates of induction (29.3%). Additionally, women in the RA group gave birth to infants with lower mean birth weights (3224±597g) and who were small for gestational age (15.6%; P <.01). Rates of maternal and neonatal mortality, infant congenital anomaly, and mean number of days spent in the neonatal intensive care unit were similar among groups.

Multivariate analyses confirmed that women with RA were significantly more likely to have a small for gestational age infant (odds ratio [OR], 1.51; 95% CI, 1.21-1.88; P <.01) and a hypertensive disorder during pregnancy (OR, 1.51; 95% CI, 1.16-1.97; P <.01) than those without inflammatory arthritis. No difference was noted between the SpA group and the group without inflammatory arthritis in regard to hypertensive disorders (OR, 1.07, 95% CI, 0.92-1.25; P =.39). Sensitivity analysis for SpA subtypes (psoriasis/psoriatic arthritis and ankylosing spondylitis) did not significantly change the maternal and neonatal outcome results.

The researchers noted several confounders that were not available for analysis, including laboratory data, disease activity and duration, education level, and smoking status.

The study researchers concluded that women with RA were at risk for worse maternal and neonatal outcomes whereas the risk for women with SpA was similar to the risk for those without inflammatory arthritis. Furthermore, they concluded that the differences in risks between the RA and SpA groups “reflects potential differences between the underlying pathophysiology of these 2 different types of [inflammatory arthritis].”

Reference

Keeling S, Bowker S, Savu A, Kaul P. A population level analysis of the differing impacts of rheumatoid arthritis and spondyloarthritis on peripartum outcomes [published online May 1, 2019]. J Rheum. doi:10.3899/jrheum.181320