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. 2025 May 1;8(5):e2510504.
doi: 10.1001/jamanetworkopen.2025.10504.

Use of Biologics During Pregnancy Among Patients With Autoimmune Conditions

Celeste L Y Ewig  1 , Yanning Wang  1   2 , Nicole E Smolinski  1   2 , Thuy Nhu Thai  3 , Sonja A Rasmussen  4   5 , Almut G Winterstein  1   2
Affiliations

Use of Biologics During Pregnancy Among Patients With Autoimmune Conditions

Celeste L Y Ewig et al. JAMA Netw Open. .

Abstract

Importance: Continuation of biologics in patients with an autoimmune condition who become pregnant involves weighing consequences of pregnancy-related changes in disease severity and potential teratogenic effects of medications. Characterization of biologic treatment patterns during pregnancy may provide insight into maternal and fetal risks and benefits.

Objective: To describe the utilization pattern of biologics in pregnant individuals with autoimmune conditions.

Design, setting, and participants: This cohort study used data from Merative MarketScan Research Databases, which contain administrative claims of commercially insured individuals in the US. Pregnant patients aged 16 to 55 years with an autoimmune condition and biologic use 6 months before conception between January 1, 2011, and December 31, 2022, were included. The data were analyzed between October 15, 2024, and February 28, 2025.

Exposure: Use of biologics for autoimmune disease after conception.

Main outcomes and measures: The proportion of patients who used biologics for Crohn disease, ulcerative colitis, psoriasis or psoriatic arthritis, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, and multiple sclerosis was assessed, and the association between underlying autoimmune disease and use of biologics during pregnancy was measured using multivariable logistic regression.

Results: A total of 6131 pregnant patients (median [IQR] age, 32 [29-36] years) with an autoimmune condition were included. The most prevalent conditions were Crohn disease (1372 patients [25.6%]) and rheumatoid arthritis (1295 patients [24.1%]). Of all patients, 4393 (71.6%; 95% CI, 70.5%-72.8%) used biologics at least once during pregnancy. Among pregnancies with live birth outcomes, biologic use declined throughout gestation, with 2981 patients (68.6% [95% CI, 67.2%-70.0%]), 2555 patients (58.8% [95% CI, 57.3%-60.3%]), and 2113 patients (48.6% [95% CI, 47.1%-50.1%]) using biologics during the first, second, and third trimesters, respectively, and 3350 patients (77.1% [95% CI, 75.8%-78.3%]) using them post partum. Compared with pregnant patients with rheumatoid arthritis, those with Crohn disease (odds ratio [OR], 7.88 [95% CI, 5.93-10.47]) and ulcerative colitis (OR, 5.35 [95% CI, 3.73-7.66]) were more likely to use biologics, while those with psoriasis or psoriatic arthritis (OR, 0.65 [95% CI, 0.52-0.80]) were less likely.

Conclusions and relevance: In this cohort study, a decline in the use of biologics for autoimmune disease was observed during the pregnancy period that rebounded only partially thereafter. Notable variations in use across autoimmune conditions suggest that indication-specific risk-benefit assessments of biologic use are needed.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Smolinski reported receiving, through inheritance, stock from Takeda, Cardinal Health, CVS Health, Edwards Lifesciences, and Baxter outside the submitted work. Prof Rasmussen reported receiving scientific advisory committee fees from Axsome Therapeutics, Harmony Biosciences, Novo Nordisk, Pfizer, and Myovant Sciences and honoraria from UpToDate and Wiley outside the submitted work. Prof Winterstein reported receiving grants from Merck and personal fees from Merck, Bayer, Ipsen, Syneos, Novo Nordisk, and Lykos outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Prevalence of Biologic Use During and After Pregnancy Among Patients With Live Births
Pregnant patients were required to have biologic use 6 months prior to conception; therefore, biologic use before the first trimester was 100%. Error bars indicate Wilson 95% CIs.
Figure 2.
Figure 2.. Association Between Autoimmune Condition and Biologic Use During Pregnancy (Live Birth Outcomes)
OR indicates odds ratio.
Figure 3.
Figure 3.. Association Between Autoimmune Condition and Biologic Use During Pregnancy (Non–Live Birth Outcomes)
OR indicates odds ratio.
See this image and copyright information in PMC

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