Research Finds Variable Biologic Use for Autoimmune Diseases During and After Pregnancy

A new cohort study found that biologic use declined in patients with autoimmune diseases during pregnancy and only partially rebounded after. The study found high levels of variation in biologic use, highlighting a need for indication-specific risk-benefit assessments of biologic use.1

According to lead investigator Celeste L. Y. Ewig, PharmD, and colleagues, to understand how factors such as newer biologics and underlying autoimmune disease in pregnant populations “are associated with treatment decisions during pregnancy, this study aimed to describe the patterns of biologic continuation during and after pregnancy across patients with varying types of autoimmune conditions. We focused on individuals with biologic use prior to conception, in whom the benefit of biologics for their underlying condition had already been established, to capture pregnancy-specific risk-benefit decisions made by clinicians and patients.”1 Ewig is a PhD candidate at the Department of Pharmaceutical Outcomes and Policy, College of Pharmacy, at the University of Florida, Gainesville.

Ewig and colleagues analyzed data from administrative claims of commercially insured individuals in the US from the Merative MarketScan Research Databases. The study included pregnant patients aged 16 to 55 years with an autoimmune condition and biologic use 6 months before conception between January 2011, and December 2022, and data were analyzed between October 2024, and February 2025.

The study primarily analyzed the proportion of patients who used biologics for Crohn disease (CD), ulcerative colitis (UC), psoriasis (PsO) or psoriatic arthritis (PsA), rheumatoid arthritis (RA), ankylosing spondylitis, systemic lupus erythematosus, and multiple sclerosis, and the association between underlying autoimmune disease and use of biologics during pregnancy using multivariable logistic regression.

Overall, the study included 6131 pregnant patients with a median age of 32 years (IQR, 29-36) with Crohn disease (n = 1372; 25.6%), rheumatoid arthritis (n = 1295; 24.1%), ulcerative colitius (n = 945; 15.4%), psoriasis or psoriatic arthritis (n = 608; 9.9%), multiple sclerosis (n = 261; 4.3%), ankylosing spondylitis (n = 184; 3.0%), systematic lupus erythematosis (n = 80; 1.3%), and/or multiple conditions (n = 1386; 22.6%).1

Ewig and colleagues found that 71.6% (n = 4393; 95% CI, 70.5-72.8) of participants used biologics at least once during pregnancy. Among pregnancies with live birth outcomes, biologic use declined throughout gestation: 68.6% (n = 2981; 95% CI, 67.2–70.0) of patients used biologics during the first trimester, 58.8% (n = 2555; 95% CI, 57.3–60.3) during the second trimester, and 48.6% (n = 2113; 95% CI, 47.1–50.1) during the third trimester. Postpartum, 77.1% (n = 3350; 95% CI, 75.8–78.3) of patients used biologics. Compared with pregnant patients with RA, those with CD were more likely to use biologics (OR, 7.88; 95% CI, 5.93–10.47), as were those with UC (OR, 5.35; 95% CI, 3.73–7.66), while patients with PsO or PsA were less likely (OR, 0.65; 95% CI, 0.52–0.80).1

“In this retrospective cohort study, use of biologics during pregnancy varied depending on the patients’ autoimmune conditions, suggesting differences in perceived or true risks and benefits. Future condition-specific studies evaluating safety and efficacy of biologics are needed to enhance our understanding of the risks and benefits of biologic use for both mother and infant,” Ewig and colleagues concluded.1

The investigators also addressed the partial rebound of biologics use after pregnancy, stating that recommendations for using biologics postpartum are consistently favorable, although this was not largely observed to be followed in the study.2 They encouraged further evaluation of factors contributing to this avoidance of biologic use, according to each autoimmune condition during and after pregnancy to improve understanding of potential gaps in care.

REFERENCES

1. Ewig CLY, Wang Y, Smolinski NE, Thai TN, Rasmussen SA, Winterstein AG. Use of Biologics During Pregnancy Among Patients With Autoimmune Conditions. JAMA Netw Open. 2025;8(5):e2510504. doi:10.1001/jamanetworkopen.2025.10504

2. Quintero OL, Amador-Patarroyo MJ, Montoya-Ortiz G, Rojas-Villarraga A, Anaya JM. Autoimmune disease and gender: plausible mechanisms for the female predominance of autoimmunity. J Autoimmun. 2012;38(2-3):J109-J119. doi:10.1016/j.jaut.2011.10.003