Poster Presentation Society of Obstetric Medicine of Australia and New Zealand ASM 2026

Anakinra use in pregnancy and lactation drug levels in maternal serum cord blood breast milk and infant serum  (#129)

Louisa Morand 1 , Matthew Burke 2 , Jacobus Ungerer 2 , Carel Pretorius 2 3 , Kurt Giuliliani 2 , Niel Archer 4 , Ling Li 5 6 , Fiona L Britton 3 7 8 , Leonie Callaway 7 , Isabelle Fassbind 9 , Tracy Risetto 10 , Trent Grundy * 11 , Katherine Poulsen * 1 3 7
  1. Department of Rheumatology, The Prince Charles Hospital, Chermside, QLD, Australia
  2. Department of Chemical Pathology, Royal Brisbane and Women's Hospital , Herston, QLD, Australia
  3. University of Queensland, St Lucia, QLD, Australia
  4. Department of Paediatrics, Cairns Hospital, Cairns North, QLD, Australia
  5. Department of Obstetric Medicine, Cairns Hospital, Cairns North, QLD, Australia
  6. Department of Endocrinology and Diabetes, Cairns Hospital, Cairns North, QLD, Australia
  7. Department of Obstetric Medicine, Royal Brisbane and Women's Hospital , Herston, QLD, Australia
  8. Department of Obstetric Medicine, Redcliffe Hospital, Redcliffe, QLD, Australia
  9. Pharmacy Department, Royal Brisbane and Women's Hospital , Herston, QLD, Australia
  10. Qld Medicines Advice & Information Service, Royal Brisbane and Women's Hospital , Herston, QLD, Australia
  11. Department of Rheumatology, Cairns Hospital, Cairns North, QLD, Australia

Background: 
 
Anakinra is a recombinant form of human interleukin‑1 receptor antagonist (IL‑1Ra). Limited evidence supports use during pregnancy and breastfeeding.1 Rheumatology guidelines support use in pregnancy for disease control.2 Anakinra is not a monoclonal antibody, hence is not susceptible to Fc-receptor-mediated transplacental transfer.2 Endogenous IL‑1Ra is present in breast milk;3 however, data on placental transfer, breast milk concentrations, and infant exposure to anakinra remain limited. 

Case: 
 
A 27‑year‑old woman with Familial Mediterranean Fever achieved disease control with anakinra, which was continued during pregnancy due to high flare risk. She delivered at 39+3 weeks and breastfed. IL‑1Ra levels were measured in maternal serum during pregnancy, cord blood at delivery, breast milk, and infant serum postpartum. 

Results: 
 
The assay cannot differentiate anakinra from endogenous IL‑1Ra. At 36 weeks, maternal trough and peak IL-1Ra levels were 49,700 ng/L and 194,240 ng/L respectively, consistent with non‑pregnant populations.4 Cord blood concentration was 1,739 ng/L, within expected ranges.5 Breast milk concentrations reflected anakinra pharmacokinetics,4 with trough levels of 498 ng/L and peak levels of 8,066 ng/L at two hours post‑dose, followed by decline. Infant serum IL‑1Ra 70 days postpartum was higher than expected (7,173 ng/L), as levels are expected to rapidly decline postpartum in a well infant.6 

Conclusion: 
 
This case suggests minimal transplacental transfer of anakinra and confirms transfer into breast milk. Elevated infant IL‑1Ra may reflect oral bioavailability, although biologically implausible, or simply increased endogenous production. Further studies are needed to confirm these findings. 

 

* These authors are co-senior authors. 

  1. Youngstein T, Hoffmann P, Gül A, Lane T, Williams R, Rowczenio DM, et al. International multi-centre study of pregnancy outcomes with interleukin-1 inhibitors. Rheumatology (Oxford). 2017;56(12):2102-2108. doi:10.1093/rheumatology/kex305
  2. Rüegg L, Pluma A, Hamroun S, Cecchi I, Perez-Garcia LF, Anderson PO, et al. EULAR recommendations for use of antirheumatic drugs in reproduction, pregnancy, and lactation: 2024 update. Ann Rheum Dis. 2025;84(6):910-926. doi:10.1016/j.ard.2025.02.023.
  3. National Institute of Child Health and Human Development. Anakinra. In: Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006–. Updated 2026 Apr 15 [cited 2026 Jun 3]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501871/
  4. Therapeutic Goods Administration. AusPAR attachment 2: extract from the Clinical Evaluation Report for anakinra [Internet]. Canberra (ACT): Australian Government Department of Health, Therapeutic Goods Administration; 2015 Oct 30 [cited 2026 Jun 3]. Available from: https://www.tga.gov.au/sites/default/files/auspar-anakinra-151030-cer.pdf
  5. The natural interleukin-1 receptor antagonist in the fetal, maternal, and amniotic fluid compartments: the effect of gestational age, fetal gender, and intrauterine infection Am J Obstet Gynecol. 1994 Oct;171(4):912-21. doi: 10.1016/s0002-9378(94)70058-3.
  6. Pediatric Reference Ranges for Proinflammatory and Anti-Inflammatory Cytokines in Cerebrospinal Fluid and Serum by Multiplexed Immunoassay J Interferon Cytokine Res. 2013 Sep;33(9):523–528. doi: 10.1089/jir.2012.0132