For clinicians
Belimumab
anti-BLyS, Benlysta
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Bottom lineBottom line: EULAR 2024 lists belimumab among non-TNFi biologics that may be used in pregnancy if needed to control maternal disease, and compatible with breastfeeding. Paternal data are limited. Individualise; a registry-informed decision.
By reproductive phase
| Phase | Position | Detail | Evidence |
|---|---|---|---|
| Pre-conception | Use if needed | May be continued to maintain control; shared decision given limited data.[2] | ●●○○low evidenceconditional |
| 1st trimester | Use if needed | Use if needed to control maternal disease.[2] | ●●○○low evidenceconditional |
| 2nd/3rd trimester | Use if needed | Use if needed; account for transplacental transfer of IgG in the second half of pregnancy.[2] | ●●○○low evidenceconditional |
| Breastfeeding | Continue | Compatible with lactation; minimal transfer of a large antibody.[2] | ●●○○low evidenceconditional |
| Paternal | Individualise | Limited paternal data; consider alternatives or individualise.[2] | ●○○○very low evidenceconditional |
Guideline comparison
| Guideline | Position | Strength |
|---|---|---|
| ACR 2020 | Conditionally recommend discontinuing at conception; conditionally recommend AGAINST continuing during pregnancy (grouped with the other biologics: limited transfer in early pregnancy but high transfer in the second half). Breastfeeding: conditionally compatible, expecting minimal transfer from the large molecular size, though there are no data. Paternal: unable to make a recommendation (limited data).[1] | Conditional (discontinue at conception; against during pregnancy); no paternal recommendation |
| EULAR 2024 | May be used in pregnancy if needed to control maternal disease (4/C); compatible with lactation (4/C); limited data in men (5/D).[2] | Oxford LoE/GoR as shown |
| BSR 2022/23 | Consider stopping at conception; use in either trimester only for severe maternal disease if no other pregnancy-compatible drugs are suitable. Breastfeeding and paternal exposure compatible (limited evidence). If used in the third trimester, avoid infant live vaccinations until 6 months of age.[3] | Verified against BSR Table 1 |
=Guideline divergence. VERIFIED DIVERGENCE. EULAR 2024 (5b) permits use in pregnancy if needed to control maternal disease (4/C); BSR 2023 advises considering stopping at conception and reserving use for severe maternal disease when no alternative is suitable. EULAR reports limited paternal data (5/D) whereas BSR marks paternal exposure compatible on limited evidence.
Key points
| Point | Evidence |
|---|---|
| Balance disease control against limited pregnancy safety data; shared decision-making.[2] | ●●○○low evidenceconditional |
Monitoring
- EULAR 2024 (footnote b): after non-TNFi bDMARD exposure in the 2nd/3rd trimester, delay infant live-attenuated vaccines for 6 months (4/C-5/D).
References
- Sammaritano LR, et al. 2020 ACR Guideline for the Management of Reproductive Health in RMD. Arthritis Rheumatol. 2020;72(3):529-556. https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.41191
- Ruegg L, et al. EULAR recommendations for antirheumatic drugs in reproduction, pregnancy, and lactation: 2024 update. Ann Rheum Dis. 2025;84(6):910-926. https://ard.eular.org/article/S0003-4967(25)00818-0/fulltext
- Russell MD, et al. BSR guideline on prescribing drugs in pregnancy and breastfeeding: immunomodulatory drugs and corticosteroids. Rheumatology (Oxford). 2023;62(4):e48-e88. https://academic.oup.com/rheumatology/article/62/4/e48/6783012